Ashnod's Altar + Geralf's Mindcrusher + Intruder Alarm + Skeleton Ship

UB identity

Commander legal

The 4 combo pieces

What must be in place

Skeleton Ship does not have summoning sickness.
Geralf's Mindcrusher does not have a +1/+1 counter on it.

How to execute it

  1. Activate Ashnod's Altar by sacrificing Geralf's Mindcrusher, adding {C}{C}.
  2. Geralf's Mindcrusher dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
  3. Geralf's Mindcrusher enters the battlefield, triggering itself and Intruder Alarm.
  4. Resolve the Geralf's Mindcrusher trigger, causing target player to mill five cards.
  5. Resolve the Intruder Alarm trigger, untapping all creatures.
  6. Activate Skeleton Ship by tapping it, putting a -1/-1 counter on Geralf's Mindcrusher.
  7. Repeat.

What the combo produces