Shalai and Hallar, Devoted Druid, Arcus Acolyte, and Ozolith, the Shattered Spire

Prerequisites

• Shalai and Hallar on the battlefield
• Devoted Druid on the battlefield
• Arcus Acolyte on the battlefield
• Ozolith, the Shattered Spire on the battlefield
• Devoted Druid does not have summoning sickness and does not have a -1/-1 counter on it

Steps

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

Results

• Infinite damage