Lifegain relies on resolving a critical mass of cheap creatures and enchantments like Hinterland Sanctifier, Amalia Benavides Aguirre, and Case of the Uneaten Feast, so Ultima's full board wipe answers everything at once including their artifacts. A second Pinnacle Starcage exiles their one and two-drops like Hinterland Sanctifier and Enlightened Confidant before they can generate value. Trim reactive counterspells like Three Steps Ahead and the slow Jace's Machinations since this matchup is about proactively clearing their board rather than countering individual spells. Keep Day of Judgment and Get Lost as additional sweeper/removal backup.