Sengir, the Dark Baron

Flying
Whenever another creature dies, put two +1/+1 counters on Sengir, the Dark Baron.
Whenever another player loses the game, you gain life equal to that player's life total as the turn began.
Partner (You can have two commanders if both have partner.)

Mask of Avacyn

Equipped creature gets +1/+2 and has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {3}

Revoke Existence

Caves of Koilos

{T}: Add {C}.
{T}: Add {W} or {B}. Caves of Koilos deals 1 damage to you.

Robe of Stars

Equipped creature gets +0/+3.
Astral Projection — {1}{W}: Equipped creature phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)
Equip {1}

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.

Damning Verdict

Destroy all creatures with no counters on them.

Ghostly Prison

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Mirror Shield

Equipped creature gets +0/+2 and has hexproof and "Whenever a creature with deathtouch blocks or becomes blocked by this creature, destroy that creature."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Path of Peril

Cleave {4}{W}{B} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Destroy all creatures [with mana value 2 or less].

Liquimetal Torque

{T}: Add {C}.
{T}: Target nonland permanent becomes an artifact in addition to its other types until end of turn.

Plains

Shield of Kaldra

Equipment named Sword of Kaldra, Shield of Kaldra, and Helm of Kaldra have indestructible.
Equipped creature has indestructible. (Damage and effects that say "destroy" don't destroy it.)
Equip {4}

Open the Armory

Search your library for an Aura or Equipment card, reveal it, put it into your hand, then shuffle.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Shatter the Sky

Each player who controls a creature with power 4 or greater draws a card. Then destroy all creatures.

Orzhov Signet

Vanquish the Horde

This spell costs {1} less to cast for each creature on the battlefield.
Destroy all creatures.

Ardenn, Intrepid Archaeologist

At the beginning of combat on your turn, you may attach any number of Auras and Equipment you control to target permanent or player.
Partner (You can have two commanders if both have partner.)

Damnation

Destroy all creatures. They can't be regenerated.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Karmic Justice

Whenever a spell or ability an opponent controls destroys a noncreature permanent you control, you may destroy target permanent that opponent controls.

Accorder's Shield

Equipped creature gets +0/+3 and has vigilance. (Attacking doesn't cause it to tap.)
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Secret Rendezvous

You and target opponent each draw three cards.

Talisman of Hierarchy

{T}: Add {C}.
{T}: Add {W} or {B}. Talisman of Hierarchy deals 1 damage to you.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Vault of Champions

Vault of Champions enters tapped unless you have two or more opponents.
{T}: Add {W} or {B}.

Fireshrieker

Equipped creature has double strike. (It deals both first-strike and regular combat damage.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Ambition's Cost

You draw three cards and you lose 3 life.

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Fracture

Destroy target artifact, enchantment, or planeswalker.

Wrath of God

Isolated Chapel

Isolated Chapel enters tapped unless you control a Plains or a Swamp.
{T}: Add {W} or {B}.

Ancient Craving

Mortify

Command Tower

Indestructibility

Enchant permanent
Enchanted permanent has indestructible. (Effects that say "destroy" don't destroy that permanent. A creature with indestructible can't be destroyed by damage.)

Hammer of Nazahn

Whenever Hammer of Nazahn or another Equipment you control enters, you may attach that Equipment to target creature you control.
Equipped creature gets +2/+0 and has indestructible.
Equip {4}

Sublime Exhalation

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

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Rise of the Dark Realms

Put all creature cards from all graveyards onto the battlefield under your control.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Crawlspace

No more than two creatures can attack you each combat.

Blood Pact

Target player draws two cards and loses 2 life.

Dawn

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Return all creature cards with power 2 or less from your graveyard to your hand.

Dusk

Destroy all creatures with power 3 or greater.

Dusk // Dawn

Sign in Blood

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Darksteel Mutation

Enchant creature
Enchanted creature is an Insect artifact creature with base power and toughness 0/1 and has indestructible, and it loses all other abilities, card types, and creature types.

Avacyn's Memorial

Indestructible
Other legendary permanents you control have indestructible.

Night's Whisper

Crushing Disappointment

Each player loses 2 life. You draw two cards.

Life's Finale

Destroy all creatures, then search target opponent's library for up to three creature cards and put them into their graveyard. Then that player shuffles.

Timely Ward

You may cast Timely Ward as though it had flash if it targets a commander.
Enchant creature
Enchanted creature has indestructible.

Sol Ring

Cathar's Shield

Equipped creature gets +0/+3 and has vigilance.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Damn

Destroy target creature. A creature destroyed this way can't be regenerated.
Overload {2}{W}{W} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Austere Command

Choose two —
• Destroy all artifacts.
• Destroy all enchantments.
• Destroy all creatures with mana value 3 or less.
• Destroy all creatures with mana value 4 or greater.

Darksteel Plate

Indestructible
Equipped creature has indestructible.
Equip {2}

Champion's Helm

Equipped creature gets +2/+2.
As long as equipped creature is legendary, it has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Colossus Hammer

Equipped creature gets +10/+10 and loses flying.
Equip {8} ({8}: Attach to target creature you control. Equip only as a sorcery.)

Shielded by Faith

Enchant creature
Enchanted creature has indestructible.
Whenever a creature enters, you may attach Shielded by Faith to that creature.