Mairsil, the Pretender + Ventifact Bottle + Magistrate's Scepter + Horseshoe Crab

Mairsil, the Pretender

Ventifact Bottle

Magistrate's Scepter

Horseshoe Crab

How it works

1. Activate Mairsil using Ventifact Bottle's ability by paying 4 and tapping it, putting three +1/+1 counters on Mairsil.
2. Activate Mairsil using Horseshoe Crab's ability by paying , untapping itself.
3. Activate Mairsil using Magistrate's Scepter's last ability by tapping it, gaining an extra turn after this one.
4. Move to your next turn.
5. Repeat.