Blood Vassal + Carnifex Demon + Cauldron of Souls + and 2 others

UBR identity

Commander legal

The 5 combo pieces

What must be in place

Mairsil does not have a -1/-1 counter on it.

How to execute it

  1. Activate Mairsil using Cauldron of Souls' ability by tapping it, giving itself persist until end of turn.
  2. Activate Mairsil using Blood Vassal's ability by sacrificing it, adding {B}{B}.
  3. When Mairsil dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
  4. Activate Mairsil using Carnifex Demon's ability by paying {B} and removing a -1/-1 counter from it, putting a -1/-1 counter on each other creature.
  5. Repeat.

What the combo produces