Sage of Hours + Master Biomancer + Soulherder

Sage of Hours

Master Biomancer

Soulherder

How it works

1. At the beginning of your end step, Soulherder's second ability triggers, blinking Sage of Hours and causing it to enter the battlefield with five or more +1/+1 counters on it due to Master Biomancer.
2. Soulherder's first ability triggers, putting a +1/+1 counter on itself.
3. Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
4. Repeat each turn.