Monk Gyatso + Lightning Greaves + Hamza, Guardian of Arashin

Monk Gyatso exiles a creature whenever it becomes the target of an ability controlled by its controller; Lightning Greaves equips for 0, triggering that exile, then fizzles because the equip has no legal target once the creature leaves. Hamza, Guardian of Arashin reduces the exiled creature's cast cost to 0 as long as two creatures with +1/+1 counters are on the battlefield, making the loop self-sustaining. The setup lives in Selesnya counter-heavy shells — Hamza as commander is the natural home since he satisfies his own cost reduction requirement.