Conjuro
Cada oponente obtiene un contador de veneno. Luego, cada criatura que controlan tus oponentes obtiene -1/-1 hasta el final del turno por cada contador de veneno que tenga su controlador.
The amount a creature's power and toughness are reduced is determined only once, at the time Phyresis Outbreak resolves. It won't change if that creature's controller later gets more poison counters or if another player takes control of it later in the same turn.