Xantcha on the battlefield under an opponent's control.
({1} magic symbol) available.
Steps
Activate Xantcha for ({1} magic symbol) , drawing a card and causing its controller to lose 2 life.
Activate Cadaverous Bloom, exiling a card from your hand and adding ({B} magic symbol) ({B} magic symbol) or ({G} magic symbol) ({G} magic symbol) .
Activate Xantcha twice using the mana generated, drawing 2 cards and losing Xantcha's controller 4 life.
Activate Cadaverous Bloom exiling a card from your hand adding ({B} magic symbol) ({B} magic symbol) or ({G} magic symbol) ({G} magic symbol) .
Repeat from step 3.
If the player controlling Xantcha reaches a point where they only have 1 or 2 life remaining, you may hold priority and activate her any number of times before the player dies and she is exiled to draw as many of the remaining cards in your library as you wish.