Plumecreed Mentor + Combine Chrysalis + Scurry Oak

Plumecreed Mentor

Combine Chrysalis

Scurry Oak

How it works

1. Cast Plumecreed Mentor by paying 1.
2. When Plumecreed Mentor enters the battlefield, it triggers, putting a +1/+1 counter on Scurry Oak.
3. Scurry Oak triggers, creating a 1/1 Squirrel creature token that has flying due to Combine Chrysalis.
4. When the Squirrel enters the battlefield, Plumecreed Mentor triggers, putting a +1/+1 counter on Scurry Oak.
5. Repeat from step 3.