Ixhel, Scion of Atraxa

Flying, vigilance, toxic 2
Corrupted — At the beginning of your end step, each opponent who has three or more poison counters exiles the top card of their library face down. You may look at and play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast those spells.

Benalish Sleeper

Kicker {B} (You may pay an additional {B} as you cast this spell.)
When Benalish Sleeper enters, if it was kicked, each player sacrifices a creature of their choice.