This elegant loop starts with any initial instance of lifegain, which triggers Light of Promise to place a +1/+1 counter on Invisible Woman, Sue Storm. That counter placement then triggers Invisible Woman, Sue Storm's ability to create a 0/4 colorless Wall creature token with defender. As that token enters the battlefield, Suture Priest recognizes the new arrival and triggers to grant you 1 life. That newly gained life immediately feeds back into Light of Promise, keeping the engine running to continuously churn out infinite creature tokens, infinite creature ETBs, infinite lifegain triggers, and an infinitely large Invisible Woman, Sue Storm.