Conjuro
Después de la primera fase principal poscombate este turno, hay una fase de combate adicional seguida de una fase principal adicional. Al comienzo de ese combate, endereza todas las criaturas que atacaron este turno.
Rebote. (Si lanzas este hechizo de tu mano, exílialo en cuanto se resuelve. Al comienzo de tu próximo mantenimiento, puedes lanzar esta carta desde el exilio sin pagar su coste de maná.)
As long as World at War resolves before the first postcombat main phase of a turn ends, it will have its full effect. That will happen in most cases, since it’s a sorcery (meaning it’s probably cast during the first or second main phase of a turn), and it has rebound (meaning it’ll be cast during your upkeep). If, however, it’s cast later than that, it won’t create any new phases. For example, if one World at War creates a second combat phase and a third main phase in a turn, then a second World at War is cast during that third main phase, no additional phases are created. The rebound effect still works, though.