Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Summon: G.F. Cerberus

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
II — Double — When you next cast an instant or sorcery spell this turn, copy it. You may choose new targets for the copy.
III — Triple — When you next cast an instant or sorcery spell this turn, copy it twice. You may choose new targets for the copies.

Coordinated Maneuver

Choose one —
• Coordinated Maneuver deals damage equal to the number of creatures you control to target creature or planeswalker.
• Destroy target enchantment.

Brass Knuckles

When you cast this spell, copy it. (The copy becomes a token.)
Equipped creature has double strike as long as two or more Equipment are attached to it.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Spider-Man, Brooklyn Visionary

Web-slinging {2}{G} (You may cast this spell for {2}{G} if you also return a tapped creature you control to its owner's hand.)
When Spider-Man enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Lord Jyscal Guado

Flying
At the beginning of each end step, if you put a counter on a creature this turn, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Hexplate Golem

Grasping Longneck

Reach
When this creature dies, you gain 2 life.

Chain Assassination

Freerunning {1}{B} (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
Destroy target creature. If another creature died this turn, draw a card.

Siphon Insight

Look at the top two cards of target opponent's library. Exile one of them face down and put the other on the bottom of that library. You may play the exiled card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.
Flashback {1}{U}{B}

Dragon's Prey

This spell costs {2} more to cast if it targets a Dragon.
Destroy target creature.

Might of the Ancestors

At the beginning of combat on your turn, target creature you control gets +2/+0 and gains vigilance until end of turn.

Fatal Push

Destroy target creature if it has mana value 2 or less.
Revolt — Destroy that creature if it has mana value 4 or less instead if a permanent left the battlefield under your control this turn.

The Spot's Portal

Put target creature on the bottom of its owner's library. You lose 2 life unless you control a Villain.

Ezio, Brash Novice

Whenever Ezio attacks, put a +1/+1 counter on it.
As long as Ezio has two or more counters on it, it has first strike and is an Assassin in addition to its other types.

Edward Kenway

At the beginning of your end step, create a Treasure token for each tapped Assassin, Pirate, and/or Vehicle you control.
Whenever a Vehicle you control deals combat damage to a player, look at the top card of that player's library, then exile it face down. You may play that card for as long as it remains exiled.

Sultai Devotee

Deathtouch
{1}: Add {B}, {G}, or {U}. Activate only once each turn.

The Lord Master of Hell

Starfall — Whenever The Lord Master of Hell attacks, it deals X damage to each opponent, where X is the number of noncreature, nonland cards in your graveyard.

The Emperor of Palamecia

{T}: Add {U} or {R}. Spend this mana only to cast a noncreature spell.
Whenever you cast a noncreature spell, if at least four mana was spent to cast it, put a +1/+1 counter on The Emperor of Palamecia. Then if it has three or more +1/+1 counters on it, transform it.

The Emperor of Palamecia // The Lord Master of Hell

Curtains' Call

Undaunted (This spell costs {1} less to cast for each opponent.)
Destroy two target creatures.

Web Up

When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.

Peculiar Lighthouse

This land enters tapped unless a player has 13 or less life.
{T}: Add {U} or {R}.

Adéwalé, Breaker of Chains

When Adéwalé enters, reveal the top six cards of your library. Put an Assassin, Pirate, or Vehicle card from among them into your hand and the rest on the bottom of your library in a random order.
Whenever a Vehicle you control deals combat damage to a player, you may return this card from your graveyard to your hand.

Oceanus Dragon

Flying
When this creature enters, tap target creature an opponent controls. Goad it. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Iridescent Tiger

When this creature enters, if you cast it, add {W}{U}{B}{R}{G}.

Puresteel Paladin

Whenever an Equipment you control enters, you may draw a card.
Metalcraft — Equipment you control have equip {0} as long as you control three or more artifacts.

Charge

Creatures you control get +1/+1 until end of turn.

Thieving Varmint

Deathtouch, lifelink
{T}, Pay 1 life: Add two mana of any one color. Spend this mana only to cast spells you don't own.

Uncanny Speed

Target creature gets +3/+0 and gains haste until end of turn.

Master Piandao

First strike
Whenever Master Piandao attacks, look at the top four cards of your library. You may reveal an Ally, Equipment, or Lesson card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Wild Ride

Target creature gets +3/+0 and gains haste until end of turn.
Harmonize {4}{R} (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by {X}, where X is its power. Then exile this spell.)

Stone Quarry

This land enters tapped.
{T}: Add {R} or {W}.

Edric, Spymaster of Trest

Whenever a creature deals combat damage to one of your opponents, its controller may draw a card.

Ether

{T}, Exile this artifact: Add {U}. When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Terrific Team-Up

This spell costs {2} less to cast if you control a permanent with mana value 4 or greater.
One or two target creatures you control each get +1/+0 until end of turn. They each deal damage equal to their power to target creature an opponent controls.

Mercurial Spelldancer

This creature can't be blocked.
Whenever you cast a noncreature spell, put an oil counter on this creature.
Whenever this creature deals combat damage to a player, you may remove two oil counters from it. If you do, when you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Jeong Jeong, the Deserter

Firebending 1 (Whenever this creature attacks, add {R}. This mana lasts until end of combat.)
Exhaust — {3}: Put a +1/+1 counter on Jeong Jeong. When you next cast a Lesson spell this turn, copy it and you may choose new targets for the copy. (Activate each exhaust ability only once.)

Curious Forager

When this creature enters, you may forage. When you do, return target permanent card from your graveyard to your hand. (To forage, exile three cards from your graveyard or sacrifice a Food.)

Brotherhood Outcast

When this creature enters, choose one —
• Return target Aura or Equipment card with mana value 3 or less from your graveyard to the battlefield.
• Put a shield counter on target creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

Ice Flan

When this creature enters, tap target artifact or creature an opponent controls. Put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Islandcycling {2} ({2}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Fire Diamond

This artifact enters tapped.
{T}: Add {R}.

Giott, King of the Dwarves

Double strike
Whenever Giott or another Dwarf you control enters and whenever an Equipment you control enters, you may discard a card. If you do, draw a card.

Insidious Fungus

{2}, Sacrifice this creature: Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Draw a card. Then you may put a land card from your hand onto the battlefield tapped.

Inspirited Vanguard

Whenever this creature enters or attacks, it endures 2. (Put two +1/+1 counters on it or create a 2/2 white Spirit creature token.)

Eyeblight Assassin

When this creature enters, target creature an opponent controls gets -1/-1 until end of turn.

Thieves' Tools

When this Equipment enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Equipped creature can't be blocked as long as its power is 3 or less.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Wick's Patrol

When this creature enters, mill three cards. When you do, target creature an opponent controls gets -X/-X until end of turn, where X is the greatest mana value among cards in your graveyard.

Fight On!

Return up to two target creature cards from your graveyard to your hand.

Chaos Wand

{4}, {T}: Target opponent exiles cards from the top of their library until they exile an instant or sorcery card. You may cast that card without paying its mana cost. Then put the exiled cards that weren't cast this way on the bottom of that library in a random order.

Diluvian Primordial

Flying
When this creature enters, for each opponent, you may cast up to one target instant or sorcery card from that player's graveyard without paying its mana cost. If a spell cast this way would be put into a graveyard, exile it instead.

Gate Colossus

Affinity for Gates (This spell costs {1} less to cast for each Gate you control.)
This creature can't be blocked by creatures with power 2 or less.
Whenever a Gate you control enters, you may put this card from your graveyard on top of your library.

Stormsplitter

Haste
Whenever you cast an instant or sorcery spell, create a token that's a copy of this creature. Exile that token at the beginning of the next end step.

Corroding Dragonstorm

When this enchantment enters, each opponent loses 2 life and you gain 2 life. Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
When a Dragon you control enters, return this enchantment to its owner's hand.

Miasma Demon

Flying
When this creature enters, you may discard any number of cards. When you do, up to that many target creatures each get -2/-2 until end of turn.

Kin-Tree Nurturer

Lifelink
When this creature enters, it endures 1. (Put a +1/+1 counter on it or create a 1/1 white Spirit creature token.)

Reputable Merchant

When this creature enters or dies, put a +1/+1 counter on target creature you control.

Inspired Charge

Creatures you control get +2/+1 until end of turn.

Oblivion Sower

When you cast this spell, target opponent exiles the top four cards of their library, then you may put any number of land cards that player owns from exile onto the battlefield under your control.

Venom's Hunger

This spell costs {2} less to cast if you control a Villain.
Destroy target creature. You gain 2 life.

Clifftop Retreat

This land enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.

Ichor Shade

At the beginning of your end step, if an artifact or creature was put into a graveyard from the battlefield this turn, put a +1/+1 counter on this creature.

Light of Judgment

Light of Judgment deals 6 damage to target creature. Destroy up to one Equipment attached to that creature.

Cathartic Reunion

As an additional cost to cast this spell, discard two cards.
Draw three cards.

Smite the Monstrous

Destroy target creature with power 4 or greater.

Grow Extra Arms

This spell costs {1} less to cast if it targets a Spider.
Target creature gets +4/+4 until end of turn.

Fear of Failed Tests

Whenever this creature deals combat damage to a player, draw that many cards.

White Lotus Reinforcements

Vigilance
Other Allies you control get +1/+1.

Lion Heart

When this Equipment enters, it deals 2 damage to any target.
Equipped creature gets +2/+1.
Equip {2}

Jeskai Monument

When this artifact enters, search your library for a basic Island, Mountain, or Plains card, reveal it, put it into your hand, then shuffle.
{1}{U}{R}{W}, {T}, Sacrifice this artifact: Create two 1/1 white Bird creature tokens with flying. Activate only as a sorcery.

Deathcoil Wurm

You may have this creature assign its combat damage as though it weren't blocked.

Foggy Swamp Vinebender

This creature can't be blocked by creatures with power 2 or less.
Waterbend {5}: Put a +1/+1 counter on this creature. Activate only during your turn. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

You're Confronted by Robbers

Choose one —
• Stall for Time — Tap up to three target creatures.
• Call for Aid — Create three 1/1 white Soldier creature tokens.

Auditore Ambush

Choose one or both —
• Return target creature to its owner's hand.
• Target player searches their library and/or graveyard for a card named Ezio, Blade of Vengeance, reveals it, and puts it into their hand. If they search their library this way, they shuffle.

Al Bhed Salvagers

Whenever this creature or another creature or artifact you control dies, target opponent loses 1 life and you gain 1 life.

Faith's Fetters

Enchant permanent
When this Aura enters, you gain 4 life.
Enchanted permanent can't attack or block, and its activated abilities can't be activated unless they're mana abilities.

Sivriss, Nightmare Speaker

{T}, Sacrifice another creature or an artifact: For each opponent, you mill a card, then return that card from your graveyard to your hand unless that player pays 3 life. (To mill a card, put the top card of your library into your graveyard.)
Choose a Background (You can have a Background as a second commander.)

Kulrath Mystic

Whenever you cast a spell with mana value 4 or greater, this creature gets +2/+0 and gains vigilance until end of turn.

Barrels of Blasting Jelly

{1}: Add one mana of any color. Activate only once each turn.
{5}, {T}, Sacrifice this artifact: It deals 5 damage to target creature.

Thirst for Identity

Draw three cards. Then discard two cards unless you discard a creature card.

Firebending Lesson

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Firebending Lesson deals 2 damage to target creature. If this spell was kicked, it deals 5 damage to that creature instead.

Item Shopkeep

Whenever you attack, target attacking equipped creature gains menace until end of turn. (It can't be blocked except by two or more creatures.)

Northern Air Temple

When Northern Air Temple enters, each opponent loses X life and you gain X life, where X is the number of Shrines you control.
Whenever another Shrine you control enters, each opponent loses 1 life and you gain 1 life.

Super Mutant Scavenger

Trample
When this creature enters or dies, return up to one target Aura or Equipment card from your graveyard to your hand.

Fleet Swallower

Whenever this creature attacks, target player mills half their library, rounded up.

Zealous Strike

Target creature gets +2/+2 and gains first strike until end of turn.

Inherited Envelope

When this artifact enters, the Ring tempts you.
{T}: Add one mana of any color.

Discreet Retreat

Enchant land
Enchanted land has "{T}: Add two mana of any one color. Spend this mana only to cast outlaw spells or activate abilities of outlaw sources." (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
Whenever you cast your first outlaw spell each turn, you draw a card and you lose 1 life.

Midnight Mayhem

Create three 1/1 red Gremlin creature tokens. Gremlins you control gain menace, lifelink, and haste until end of turn. (A creature with menace can't be blocked except by two or more creatures.)

Act of Heroism

Untap target creature. It gets +2/+2 until end of turn and can block an additional creature this turn.

Earth Rumble Wrestlers

Reach
This creature gets +1/+0 and has trample as long as you control a land creature or a land entered the battlefield under your control this turn.

Resentful Revelation

Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
Flashback {6}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Heartless Conscription

Exile all creatures. For each card exiled this way, you may play that card for as long as it remains exiled, and mana of any type can be spent to cast that spell. Exile Heartless Conscription.

Wingspan Stride

Enchant creature
Enchanted creature gets +1/+1 and has flying.
{2}{U}: Return this Aura to its owner's hand.

Magicked Card

Flying
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Sidequest: Card Collection

When this enchantment enters, draw three cards, then discard two cards.
At the beginning of your end step, if eight or more cards are in your graveyard, transform this enchantment.

Sidequest: Card Collection // Magicked Card

Tavern Brawler

Commander creatures you own have "At the beginning of your upkeep, exile the top card of your library. This creature gets +X/+0 until end of turn, where X is that card's mana value. You may play that card this turn."

Light Up the Stage

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Seifer Almasy

Whenever a creature you control attacks alone, it gains double strike until end of turn.
Fire Cross — Whenever Seifer Almasy deals combat damage to a player, you may cast target instant or sorcery card with mana value 3 or less from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Kill Shot

Guiding Bolt

Destroy target creature with power 4 or greater.
Scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Brotherhood Spy

At the beginning of combat on your turn, if you control a legendary Assassin, this creature gets +1/+0 until end of turn and can't be blocked this turn.