Sacrifice a creature: Add {C}{C}.

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

Blasphemous Act deals 13 damage to each creature.

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Flying

Whenever Butcher of Malakir or another creature you control dies, each opponent sacrifices a creature.

{2}, {T}: Add {B} for each Swamp you control.

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

Flash

Whenever a creature you control dies, each opponent sacrifices a creature.

{1}, {T}: Add {U}{B}.

Creatures you control get +1/+1 and have flying and indestructible.

At the beginning of your upkeep, sacrifice a creature. If you can't, sacrifice Eldrazi Monument.

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

{2}, {T}, Sacrifice Expedition Map: Search your library for a land card, reveal it, put it into your hand, then shuffle.

{T}: Add {C}.

{T}: Choose target commander that entered the battlefield this turn. Put a +1/+1 counter on it if it's a creature and a loyalty counter on it if it's a planeswalker.

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.

Whenever a creature you control dies, each other player sacrifices a creature.

Morph {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.)

Whenever another nontoken creature you control dies, draw a card.

Creatures you control with +1/+1 counters on them can't be blocked.

{T}: Add {C}.

{T}, Sacrifice a creature: You gain 1 life.

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)

Equip {0}

Dethrone (Whenever this creature attacks the player with the most life or tied for most life, put a +1/+1 counter on it.)

Other creatures you control have dethrone.

Whenever a creature you control with a +1/+1 counter on it dies, return that card to the battlefield under your control at the beginning of the next end step.

Gain control of target creature until end of turn. Put a +1/+1 counter on it and untap it. That creature gains haste until end of turn. (It can attack and {T} this turn.)

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Whenever a Human deals damage to you, destroy it.

Other non-Human creatures you control get +1/+1 and have undying. (When a creature with undying dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Myriad Landscape enters the battlefield tapped.

{T}: Add {C}.

{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Nevinyrral's Disk enters the battlefield tapped.

{1}, {T}: Destroy all artifacts, creatures, and enchantments.

{T}: Add {C}.

{1}, {T}: Add one mana of any color in your commander's color identity. If you spend this mana to cast your commander, it enters the battlefield with a number of additional +1/+1 counters on it equal to the number of times it's been cast from the command zone this game.

Whenever you cast a spell from your graveyard, draw a card.

Deathtouch

Exploit (When this creature enters the battlefield, you may sacrifice a creature.)

When Sidisi, Undead Vizier exploits a creature, you may search your library for a card, put it into your hand, then shuffle.

Flying

{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Equipped creature gets +1/-1.

Whenever equipped creature dies, draw two cards.

Equip {1}

{T}: Add {C}{C}.

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

When Solemn Simulacrum dies, you may draw a card.

{T}: Add {C}{C}. Activate only if you control five or more lands.

Pay 3 life: Put a +1/+1 counter on target creature.

Choose two target creature cards in your graveyard. Sacrifice a creature. If you do, return the chosen cards to the battlefield tapped.

Haste

Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni, Undying Partisan.

Sacrifice another creature: Yahenni gains indestructible until end of turn.