Maybe

Lurrus of the Dream-Den

Companion — Each permanent card in your starting deck has mana value 2 or less. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Lifelink
Once during each of your turns, you may cast a permanent spell with mana value 2 or less from your graveyard.

Junk Diver

Flying
When Junk Diver dies, return another target artifact card from your graveyard to your hand.

Shirei, Shizo's Caretaker

Whenever a creature with power 1 or less is put into your graveyard from the battlefield, you may return that card to the battlefield at the beginning of the next end step if Shirei, Shizo's Caretaker is still on the battlefield.

Culling Dais

{T}, Sacrifice a creature: Put a charge counter on Culling Dais.
{1}, Sacrifice Culling Dais: Draw a card for each charge counter on Culling Dais.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Deadbridge Chant

When Deadbridge Chant enters, mill ten cards.
At the beginning of your upkeep, choose a card at random in your graveyard. If it's a creature card, put it onto the battlefield. Otherwise, put it into your hand.

Silumgar Assassin

Creatures with power greater than Silumgar Assassin's power can't block it.
Megamorph {2}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When Silumgar Assassin is turned face up, destroy target creature with power 3 or less an opponent controls.

Wall of Nets

Defender (This creature can't attack.)
At end of combat, exile all creatures blocked by Wall of Nets.
When Wall of Nets leaves the battlefield, return all cards exiled with Wall of Nets to the battlefield under their owners' control.

Faith's Reward

Return to the battlefield all permanent cards in your graveyard that were put there from the battlefield this turn.

Cool

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Have

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Abdel Adrian, Gorion's Ward

When Abdel Adrian, Gorion's Ward enters, exile any number of other nonland permanents you control until Abdel Adrian leaves the battlefield. Create a 1/1 white Soldier creature token for each permanent exiled this way.
Choose a Background (You can have a Background as a second commander.)

Animate Dead

Enchant creature card in a graveyard
When Animate Dead enters, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with Animate Dead." Return enchanted creature card to the battlefield under your control and attach Animate Dead to it. When Animate Dead leaves the battlefield, that creature's controller sacrifices it.
Enchanted creature gets -1/-0.

Saw in Half

Destroy target creature. If that creature dies this way, its controller creates two tokens that are copies of that creature, except their power is half that creature's power and their toughness is half that creature's toughness. Round up each time.

Glimmerpoint Stag

Vigilance
When Glimmerpoint Stag enters, exile another target permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Myrkul, Lord of Bones

As long as your life total is less than or equal to half your starting life total, Myrkul, Lord of Bones has indestructible.
Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of that card, except it's an enchantment and loses all other card types.

Circuit Mender

When Circuit Mender enters, you gain 2 life.
When Circuit Mender leaves the battlefield, draw a card.

Preston, the Vanisher

Whenever another nontoken creature you control enters, if it wasn't cast, create a token that's a copy of that creature, except it's a 0/1 white Illusion.
{1}{W}, Sacrifice five Illusions: Exile target nonland permanent.

Lord

Corpse Knight

Whenever another creature you control enters, each opponent loses 1 life.

Jaddi Offshoot

Defender
Landfall — Whenever a land you control enters, you gain 1 life.

Illusionist's Bracers

Whenever an ability of equipped creature is activated, if it isn't a mana ability, copy that ability. You may choose new targets for the copy.
Equip {3}

Mentor of the Meek

Whenever another creature you control with power 2 or less enters, you may pay {1}. If you do, draw a card.

Unhallowed Pact

Enchant creature
When enchanted creature dies, return that card to the battlefield under your control.

Ruthless Technomancer

When Ruthless Technomancer enters, you may sacrifice another creature you control. If you do, create a number of Treasure tokens equal to that creature's power.
{2}{B}, Sacrifice X artifacts: Return target creature card with power X or less from your graveyard to the battlefield. X can't be 0.

Pawn of Ulamog

Whenever Pawn of Ulamog or another nontoken creature you control dies, you may create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this creature: Add {C}."

Body Count

Spectacle {B} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Draw a card for each creature that died under your control this turn.

Necrogen Communion

Enchant creature you control
Enchanted creature has toxic 2. (Players dealt combat damage by it also get two poison counters.)
When enchanted creature dies, return that card to the battlefield under your control.

Priest of Forgotten Gods

{T}, Sacrifice two other creatures: Any number of target players each lose 2 life and sacrifice a creature of their choice. You add {B}{B} and draw a card.

Apprentice Necromancer

{B}, {T}, Sacrifice Apprentice Necromancer: Return target creature card from your graveyard to the battlefield. That creature gains haste. At the beginning of the next end step, sacrifice it.

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker of their choice. Each player who can't discards a card.

Splash Lord

Dreadhound

When Dreadhound enters, mill three cards. (Put the top three cards of your library into your graveyard.)
Whenever a creature dies or a creature card is put into a graveyard from a library, each opponent loses 1 life.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Weathered Bodyguards

As long as Weathered Bodyguards is untapped, all combat damage that would be dealt to you by unblocked creatures is dealt to Weathered Bodyguards instead.
Morph {3}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Fleshbag Marauder

When Fleshbag Marauder enters, each player sacrifices a creature of their choice.

Minion's Return

Flash
Enchant creature
When enchanted creature dies, return that card to the battlefield under your control.

Cost critical

Debtors' Knell

({W/B} can be paid with either {W} or {B}.)
At the beginning of your upkeep, put target creature card from a graveyard onto the battlefield under your control.

Scorn-Blade Berserker

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
{1}, Sacrifice this creature: Draw a card.

Sun Titan

Vigilance
Whenever Sun Titan enters or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Cathar Commando

Flash (You may cast this spell any time you could cast an instant.)
{1}, Sacrifice this creature: Destroy target artifact or enchantment.

Bone Shards

As an additional cost to cast this spell, sacrifice a creature or discard a card.
Destroy target creature or planeswalker.

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Kazandu Nectarpot

Landfall — Whenever a land you control enters, you gain 1 life.

Tragic Poet

{T}, Sacrifice Tragic Poet: Return target enchantment card from your graveyard to your hand.

Drivnod, Carnage Dominus

If a creature dying causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{B/P}{B/P}, Exile three creature cards from your graveyard: Put an indestructible counter on Drivnod, Carnage Dominus. ({B/P} can be paid with either {B} or 2 life.)

Anguished Unmaking

Exile target nonland permanent. You lose 3 life.

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Yawgmoth, Thran Physician

Protection from Humans
Pay 1 life, Sacrifice another creature: Put a -1/-1 counter on up to one target creature and draw a card.
{B}{B}, Discard a card: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Sifter of Skulls

Devoid (This card has no color.)
Whenever another nontoken creature you control dies, create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this creature: Add {C}." ({C} represents colorless mana.)

Thieving Amalgam

At the beginning of each opponent's upkeep, you manifest the top card of that player's library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Whenever a creature you control but don't own dies, its owner loses 2 life and you gain 2 life.

Kami of False Hope

Sacrifice Kami of False Hope: Prevent all combat damage that would be dealt this turn.

Plague Reaver

At the beginning of your end step, sacrifice each other creature you control.
Discard two cards, Sacrifice Plague Reaver: Choose target opponent. Return Plague Reaver to the battlefield under that player's control at the beginning of their next upkeep.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Merciless Executioner

When Merciless Executioner enters, each player sacrifices a creature of their choice.

Soul-Strike Technique

Enchant creature
Enchanted creature gets +1/+1 and has vigilance.
When enchanted creature dies, manifest the top card of your library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Midnight Reaper

Whenever a nontoken creature you control dies, this creature deals 1 damage to you and you draw a card.

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Eerie Interlude

Exile any number of target creatures you control. Return those cards to the battlefield under their owner's control at the beginning of the next end step.

Liege of the Pit

Flying, trample
At the beginning of your upkeep, sacrifice a creature other than Liege of the Pit. If you can't, Liege of the Pit deals 7 damage to you.
Morph {B}{B}{B}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Shigeki, Jukai Visionary

{1}{G}, {T}, Return Shigeki, Jukai Visionary to its owner's hand: Reveal the top four cards of your library. You may put a land card from among them onto the battlefield tapped. Put the rest into your graveyard.
Channel — {X}{X}{G}{G}, Discard Shigeki: Return X target nonlegendary cards from your graveyard to your hand.

Ratadrabik of Urborg

Vigilance, ward {2}
Other Zombies you control have vigilance.
Whenever another legendary creature you control dies, create a token that's a copy of that creature, except it's not legendary and it's a 2/2 black Zombie in addition to its other colors and types.

Whisperwood Elemental

At the beginning of your end step, manifest the top card of your library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Sacrifice Whisperwood Elemental: Until end of turn, face-up nontoken creatures you control gain "When this creature dies, manifest the top card of your library."

Eerie Ultimatum

Return any number of permanent cards with different names from your graveyard to the battlefield.

Selfless Savior

Sacrifice Selfless Savior: Another target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Eaten Alive

As an additional cost to cast this spell, sacrifice a creature or pay {3}{B}.
Exile target creature or planeswalker.

Tayam, Luminous Enigma

Each other creature you control enters with an additional vigilance counter on it.
{3}, Remove three counters from among creatures you control: Mill three cards, then return a permanent card with mana value 3 or less from your graveyard to the battlefield.

Haunted Cadaver

Whenever Haunted Cadaver deals combat damage to a player, you may sacrifice it. If you do, that player discards three cards.
Morph {1}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Bushmeat Poacher

{1}, {T}, Sacrifice another creature: You gain life equal to the sacrificed creature's toughness. Draw a card.

Don't Have

Phyrexian Dreadnought

Trample
When Phyrexian Dreadnought enters, sacrifice it unless you sacrifice any number of creatures with total power 12 or greater.

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Scroll of Fate

{T}: Manifest a card from your hand. (Put that card onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Retreat to Hagra

Landfall — Whenever a land you control enters, choose one —
• Target creature gets +1/+0 and gains deathtouch until end of turn.
• Each opponent loses 1 life and you gain 1 life.

Shambling Ghast

When Shambling Ghast dies, choose one —
• Target creature an opponent controls gets -1/-1 until end of turn.
• Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Necrosynthesis

Enchant creature
Enchanted creature has "Whenever another creature dies, put a +1/+1 counter on this creature."
When enchanted creature dies, look at the top X cards of your library, where X is its power. Put one of those cards into your hand and the rest on the bottom of your library in a random order.

Salvage Scout

{W}, Sacrifice Salvage Scout: Return target artifact card from your graveyard to your hand.

Lacks synergy

Conduit of Worlds

You may play lands from your graveyard.
{T}: Choose target nonland permanent card in your graveyard. If you haven't cast a spell this turn, you may cast that card. If you do, you can't cast additional spells this turn. Activate only as a sorcery.

Cruel Celebrant

Whenever Cruel Celebrant or another creature or planeswalker you control dies, each opponent loses 1 life and you gain 1 life.

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

Dark Prophecy

Whenever a creature you control dies, you draw a card and you lose 1 life.

Benevolent Bodyguard

Sacrifice Benevolent Bodyguard: Target creature you control gains protection from the color of your choice until end of turn.

Dockside Chef

{1}{B}, Sacrifice an artifact or creature: Draw a card.

Cankerbloom

{1}, Sacrifice Cankerbloom: Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Saffi Eriksdotter

Sacrifice Saffi Eriksdotter: When target creature is put into your graveyard this turn, return that card to the battlefield.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Flicker

Exile target nontoken permanent, then return it to the battlefield under its owner's control.

Daxos, Blessed by the Sun

Daxos's toughness is equal to your devotion to white. (Each {W} in the mana costs of permanents you control counts toward your devotion to white.)
Whenever another creature you control enters or dies, you gain 1 life.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina, Soul Steeper gets +X/+0 until end of turn, where X is the sacrificed creature's power.

Tireless Tracker

Landfall — Whenever a land you control enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, put a +1/+1 counter on Tireless Tracker.

Liliana, Dreadhorde General

Whenever a creature you control dies, draw a card.
+1: Create a 2/2 black Zombie creature token.
−4: Each player sacrifices two creatures of their choice.
−9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.

Lolth, Spider Queen

Whenever a creature you control dies, put a loyalty counter on Lolth, Spider Queen.
0: You draw a card and you lose 1 life.
−3: Create two 2/1 black Spider creature tokens with menace and reach.
−8: You get an emblem with "Whenever an opponent is dealt combat damage by one or more creatures you control, if that player lost less than 8 life this turn, they lose life equal to the difference."

Magus of the Mirror

{T}, Sacrifice Magus of the Mirror: Exchange life totals with target opponent. Activate only during your upkeep.

Disciple of Perdition

When Disciple of Perdition dies, choose one. If you have exactly 13 life, you may choose both instead.
• You draw a card and you lose 1 life.
• Exile target opponent's graveyard. That player loses 1 life.

Ashnod's Altar

Cryptic Trilobite

Cryptic Trilobite enters with X +1/+1 counters on it.
Remove a +1/+1 counter from Cryptic Trilobite: Add {C}{C}. Spend this mana only to activate abilities.
{1}, {T}: Put a +1/+1 counter on Cryptic Trilobite.

Grave Betrayal

Whenever a creature you don't control dies, return it to the battlefield under your control with an additional +1/+1 counter on it at the beginning of the next end step. That creature is a black Zombie in addition to its other colors and types.

Novice Occultist

When Novice Occultist dies, you draw a card and you lose 1 life.