Requires

Burakos, Party Leader must be on the battlefield. Haunted One must be on the battlefield. Relic of Legends must be on the battlefield. Merciless Executioner must be in hand. Retribution of the Ancients must be on the battlefield. Burakos, Party Leader must be your commander. Burakos does not have a +1/+1 counter on it. Mana needed:

Steps

1. Cast Merciless Executioner by paying .
2. When Merciless Executioner enters the battlefield, it triggers.
3. Holding priority, activate Relic of Legends' second ability by tapping Burakos, adding .
4. Burakos triggers, giving it and all creatures you control that share a creature type with it +2/+0 and undying until end of turn.
5. Resolve the Merciless Executioner trigger from step 2, causing you to sacrifice Burakos, and each opponent to sacrifice a creature.
6. When Burakos dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
7. Activate Retribution of the Ancients by paying and removing the +1/+1 counter from Burakos, giving Merciless Executioner -1/-1 until end of turn.
8. Merciless Executioner dies as a state-based action due to having 0 toughness, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter from it.
9. Repeat steps 2 through 6 one additional time.
10. Activate Retribution of the Ancients by paying and removing the +1/+1 counter from Burakos and Merciless Executioner, giving Merciless Executioner -2/-2 until end of turn.
11. Repeat from step 8.

Results