This loop sets up a self-sustaining cycle of life and growth by connecting triggered abilities across your board. It all begins when you gain life, which causes Spider-Man, Peter Parker to place a +1/+1 counter on Herd Baloth. That influx of counters makes Herd Baloth trigger to create a 4/4 green Beast token, whose arrival on the battlefield prompts Hinterland Sanctifier to give you more life. That new life restarts Spider-Man, Peter Parker's trigger, letting you endlessly pump Herd Baloth with counters while flooding the board with infinite tokens, life, and enter-the-battlefield triggers.