Shalai and Hallar + Devoted Druid + Arcus Acolyte + Conclave Mentor

Shalai and Hallar

Devoted Druid

Arcus Acolyte

Conclave Mentor

How it works

1. Activate Devoted Druid's first ability by tapping it, adding .
2. Activate Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
3. If Devoted Druid has a +1/+1 counter on it, repeat from step 1 until Devoted Druid has no +1/+1 counters.
4. Activate Devoted Druid's outlast ability by paying and tapping it, putting two +1/+1 counters on Devoted Druid.
5. Shalai and Hallar triggers, dealing 2 damage to an opponent.
6. Repeat from step 2.