Cast Whitemane Lion by paying 0 and 2 life due to Defiler of Faith and Oketra's Monument.
Defiler of Faith and Oketra's Monument trigger.
Resolve the Defiler of Faith trigger, creating a 1/1 Soldier creature token.
When the Soldier enters, Elas il-Kor triggers, causing you to gain life.
Resolve the Oketra's Monument trigger, creating a 1/1 Warrior creature token.
When the Warrior enters, Elas il-Kor triggers, causing you to gain life.
Resolve Whitemane Lion. When it enters, it and Elas il-Kor trigger.
Resolve the Whitemane Lion trigger, returning it from the battlefield to your hand.
Resolve the Elas il-Kor trigger, causing you to gain life.
Repeat.
This clever loop relies on cost reducers to cast Whitemane Lion for free—fueled by Defiler of Faith paying life instead of white mana and Oketra's Monument shaving off generic mana. Every time the Lion enters the battlefield, its own ability bounces it right back to your hand, while Elas il-Kor, Sadistic Pilgrim capitalizes on the revolving door by continuously padding your life total with its life-gain triggers. Meanwhile, the mere casting of the creature triggers both Defiler of Faith and Oketra's Monument to flood the board with an endless army of Soldier and Warrior tokens.