This delightful loop is powered by a clever marriage of lifegain triggers and token generation: any initial instance of lifegain lets Heliod, Sun-Crowned place a +1/+1 counter on Scurry Oak. That influx of power immediately provokes Scurry Oak into spawning a 1/1 Squirrel token, which in turn causes Elas il-Kor, Sadistic Pilgrim to trigger and grant you 1 life upon entering the battlefield. Because that new lifegain event feeds right back into Heliod, Sun-Crowned, the cycle becomes completely self-sustaining, flooding your board with an endless army of tokens while draining your opponents out of the game.