Mikaeus, the Unhallowed + Triskelion

Prerequisites

Triskelion has at least two +1/+1 counters on it.

Steps

1. If Triskelion has at least three +1/+1 counters on it, activate Triskelion by removing a +1/+1 counter from it, dealing 1 damage to any target.
2. Repeat step 1 until there are two +1/+1 counters remaining on Triskelion.
3. Activate Triskelion by removing a +1/+1 counter from Triskelion, dealing 1 damage to itself.
4. Repeat step 3 an additional time.
5. Triskelion dies.
6. Triskelion's undying ability triggers, returning it to the battlefield with an additional +1/+1 counter on it.
7. Repeat.