Cathars' Crusade + Nest of Scarabs + Barrenton Medic

Cathars' Crusade

Nest of Scarabs

Barrenton Medic

How it works

1. Activate Barrenton Medic's first ability by tapping it, preventing the next one damage done to it this turn.
2. Activate Barrenton Medic's second ability by putting a -1/-1 counter on it.
3. Nest of Scarabs triggers, creating a 1/1 Insect creature token.
4. The Insect enters the battlefield, triggering Cathars' Crusade, putting a +1/+1 counter on each creature you control.
5. Resolve the Barrenton Medic ability from step 2, untapping it.
6. Repeat.