Mask of the Mimic

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a card with the same name as target nontoken creature, put that card onto the battlefield, then shuffle.

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

Grim Reminder

Search your library for a nonland card and reveal it. Each opponent who cast a spell this turn with the same name as that card loses 6 life. Then shuffle.
{B}{B}: Return Grim Reminder from your graveyard to your hand. Activate only during your upkeep.