When you play a unit with 4 Strength or more, it gets Aegis.
Svetya's Agenda: Wisdom of the Elders, Withstand, Sack the City.
Card sounds may differ from in-game as they get updated.
Aegis - Aegis protects a unit or player from one enemy spell or effect. It doesn't block friendly effects, nor does it stop battle damage from Killer attacks, Relic Weapons, or normal attack and blocking.