Rite of Passage + Walking Ballista + Loading Zone

Rite of Passage

Walking Ballista

Loading Zone

How it works

1. Activate Walking Ballista by removing a +1/+1 counter from it, dealing 1 damage to itself.
2. Rite of Passage triggers, putting two +1/+1 counters on Walking Ballista.
3. Repeat an arbitrarily large number of times.
4. Move to the next turn, removing all damage marked on Walking Ballista.
5. Activate Walking Ballista by removing a +1/+1 counter from it, dealing 1 damage to any target.
6. Repeat step 5 as desired.

This delightful loop centers around Walking Ballista turning its own self-inflicted harm into exponential growth. When you use Walking Ballista's ability to ping itself, Rite of Passage triggers to reward that survival with a +1/+1 counter, but Loading Zone doubles that reward into two counters for every single instance of damage. Because you net a positive number of counters on each cycle, you can repeat the process to grow Walking Ballista to astronomical sizes before finally turning those counters into infinite damage aimed anywhere you please.