Mikaeus, the Unhallowed + Workhorse + Skullclamp

Mikaeus, the Unhallowed

Workhorse

Skullclamp

How it works

1. Activate Workhorse by removing a +1/+1 counter from it, adding C.
2. Repeat step 1 until Workhorse does not have any +1/+1 counters on it.
3. Activate Skullclamp's equip ability by paying 1, attaching it to Workhorse.
4. Workhorse dies as a state-based action due to having zero toughness, triggering its undying ability and Skullclamp.
5. Resolve the Workhorse trigger, returning it from your graveyard to the battlefield with five +1/+1 counters on it.
6. Resolve the Skullclamp trigger, causing you to draw two cards.
7. Repeat.

This clever loop turns Workhorse into an endless engine of sacrifice and rebirth by exploiting its own modular counters. You begin by stripping away Workhorse's starting counters for mana, and then use Skullclamp's lethal toughness reduction to send the creature straight to the graveyard. At that exact moment, Mikaeus, the Unhallowed steps in with his passive lord effect, granting Workhorse undying so it returns to the battlefield with a fresh set of +1/+1 counters ready to repeat the cycle.