Rowan, Scion of War + Exsanguinate + Koh, the Face Stealer

Rowan, Scion of War

Exsanguinate

Koh, the Face Stealer

How it works

1. Activate Koh by paying life.
2. Repeat step 1 as desired.
3. Activate Rowan by tapping it, reducing the cost of all black and/or red spells you cast this turn.
4. Cast Exsanguinate, choosing for X to equal the amount of life you've lost this turn, but paying a total of due to Rowan.
5. Resolve Exsanguinate, causing each opponent to lose X life, and you to gain life equal to the life lost this way.