Defiler of Faith + The Wind Crystal + Soul's Attendant + Kor Skyfisher

Defiler of Faith

The Wind Crystal

Soul's Attendant

Kor Skyfisher

How it works

1. Cast Kor Skyfisher by paying 0 and 2 life due to Defiler of Faith and The Wind Crystal.
2. Defiler of Faith triggers, creating a 1/1 Soldier creature token.
3. When the Soldier enters, Soul's Attendant triggers, causing you to gain life.
4. Resolve Kor Skyfisher. When it enters, it and Soul's Attendant trigger.
5. Resolve the Kor Skyfisher trigger, returning it from the battlefield to your hand.
6. Resolve the Soul's Attendant trigger, causing you to gain life.
7. Repeat.

This engine turns Kor Skyfisher into a self-returning loop by using cost reducers to completely eliminate its mana requirement. With both Defiler of Faith and The Wind Crystal on the board, the creature's mana cost is reduced to zero, allowing you to cast it repeatedly while Defiler of Faith creates a 1/1 white Soldier creature token upon each casting. Every time a creature enters the battlefield, Soul's Attendant triggers to pad your life total, a gain further doubled by The Wind Crystal's replacement effect. Finally, Kor Skyfisher's own entry trigger forces you to bounce a permanent, which conveniently targets the Kor Skyfisher itself so you can cast it all over again.