Lifegain relies on a wide swarm of small, lifegain-triggering creatures like Hinterland Sanctifier, Deep-Cavern Bat, and Moseo, so Vicious Rivalry can wipe their early board of cheap creatures for a low life payment before they establish an engine. Dragon Sniper's deathtouch and reach trade efficiently with their small bodies and can block down fliers like Deep-Cavern Bat or Starscape Cleric. Ouroboroid is too slow to matter before they stabilize with lifegain, and Commune with Beavers doesn't answer their board development, so both get trimmed for proactive removal. Prioritize sweeping their early plays before Amalia Benavides Aguirre's explore triggers or Moseo's recursion engine gets out of hand.