Reveillark + Nim Deathmantle + Ashnod's Altar + at least one nontoken creature with power 2 or less = infinite sacrifices, ETBs, and recursion of creatures with power 2 or less (Interesting ones listed here)
How it works:
- Sacrifice Reveillark and another noncreature token with power 2 or less to Ashnod's Altar, making 4 colorless mana and triggering both Nim Deathmantle's ability and Reveillark's leave the battlefield ability targetting the other creature and up to one other creature with power 2 or less in your graveyard
- Pay 4 to return Reveillark attached to Nim Deathmantle using Nim Deathmantle's ability and return the other creature with Reveillark's leave the battlefield ability
- Repeat