Agatha's Soul Cauldron + Heroes' Bane + Crystalline Crawler

Agatha's Soul Cauldron

Heroes' Bane

Crystalline Crawler

How it works

1. Activate Crystalline Crawler using Heroes' Bane's ability by paying 2, putting a number of +1/+1 counters on Crystalline Crawler equal to its power.
2. Activate Crystalline Crawler's first ability four times by removing four +1/+1 counters from it, adding 2.
3. Repeat.