Spark Double + Murderous Redcap + Viscera Seer

Spark Double

Murderous Redcap

Viscera Seer

How it works

1. Cast Spark Double choosing to have it enter as a copy of Murderous Redcap, dealing 3 damage to any target.
2. Sacrifice the Spark Double to Viscera Seer, triggering persist.
3. The -1/-1 counter from persist and the +1/+1 counter from Spark Double cancel each other out and you deal 2 damage to any target.
4. Repeat until opponent are dead.