Hysterical Blindness

Instant

Creatures your opponents control get -4/-0 until end of turn.

2011-09-22:
Only creatures controlled by your opponent when Hysterical Blindness resolves will get -4/-0. Creatures that enter the battlefield or that an opponent gains control of later in the turn will be unaffected.
2011-09-22:
Hysterical Blindness’s effect will continue to apply to a creature even if you (or a teammate) gains control of that creature later in the turn.