Soul of Theros is a mythic Creature — Avatar card from Magic Online Promos (PRM), collector number 62471.
Vigilance {4}{W}{W}: Creatures you control get +2/+2 and gain first strike and lifelink until end of turn. {4}{W}{W}, Exile this card from your graveyard: Creatures you control get +2/+2 and gain first strike and lifelink until end of turn.