Sigil Captain + Rosie Cotton of South Lane + Crystalline Crawler + Ooze Flux + Primal Vigor

Sigil Captain

Rosie Cotton of South Lane

Crystalline Crawler

Ooze Flux

Primal Vigor

How it works

1. Activate Ooze Flux by paying 1 and removing a +1/+1 counter from a creature you control, creating two 1/1 Ooze creature tokens.
2. Rosie Cotton of South Lane triggers twice, putting two +1/+1 counters on Crystalline Crawler and any other creature you control due to Primal Vigor.
3. When the Oozes enters the battlefield, Sigil Captain triggers twice, putting four +1/+1 counters on each of them due to Primal Vigor.
4. Activate Crystalline Crawler's first ability twice by removing two +1/+1 counters from it, adding 1.
5. Repeat.