Demonic Tutor

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

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Swamp

Grave Pact

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

Dark Ritual

Terminate

Destroy target creature. It can't be regenerated.

Thraximundar

Haste
Whenever Thraximundar attacks, defending player sacrifices a creature of their choice.
Whenever a player sacrifices a creature, you may put a +1/+1 counter on Thraximundar.

Island

Mountain

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature of their choice.

Tevesh Szat, Doom of Fools

+2: Create two 0/1 black Thrull creature tokens.
+1: You may sacrifice another creature or planeswalker. If you do, draw two cards, then draw another card if the sacrificed permanent was a commander.
−10: Gain control of all commanders. Put all commanders from the command zone onto the battlefield under your control.
Tevesh Szat, Doom of Fools can be your commander.
Partner

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Jeska, Thrice Reborn

Jeska, Thrice Reborn enters with a loyalty counter on her for each time you've cast a commander from the command zone this game.
0: Choose target creature. Until your next turn, if that creature would deal combat damage to one of your opponents, it deals triple that damage to that player instead.
−X: Jeska, Thrice Reborn deals X damage to each of up to three targets.
Jeska, Thrice Reborn can be your commander.
Partner