Lifegain relies heavily on enchantments like Lunar Convocation and Case of the Uneaten Feast to drain us and generate value, so Heritage Reclamation can destroy those engines before they take over the game. Defend the Rider protects our threats from their removal (Requiting Hex) and helps us push through a grindy lifegain shell. Spell Pierce is largely dead since this is a creature-based midrange deck that isn't spell-dependent early, so it comes out along with the slower Terrian, World Tyrant and a Lumbering Worldwagon that don't pressure a deck gaining life faster than we can chip away.