Basalt Monolith + Agatha of the Vile Cauldron + Workshop Elders

Basalt Monolith

Agatha of the Vile Cauldron

Workshop Elders

How it works

1. At the beginning of your combat phase, Workshop Elders triggers, causing Basalt Monolith to become a 0/0 artifact creature, then putting four +1/+1 counters on it.
2. Activate Basalt Monolith's first ability by tapping it, adding CCC.
3. activate Basalt Monolith's second ability by paying at most 2, untapping it.
4. Repeat from step 2.