Lifelink (Damage dealt by this creature also causes you to gain that much life.) As long as you have 30 or more life, Serra Ascendant gets +5/+5 and has flying.
Official Rulings for Serra Ascendant
8/15/2010 : In a Two-Headed Giant game, anything that cares about your life total checks your team's life total. (This is a change from previous rules.) Serra Ascendant gets +5/+5 and has flying as long as your team has 30 or more life.