Pain Magnification

Oracle Text

Whenever an opponent is dealt 3 or more damage by a single source, that player discards a card.

Card Rulings

5/1/2006 This triggers only if all 3 or more damage is dealt at the same time. It doesn’t trigger if damage that adds up to 3 or more is dealt at different times by the same source.
5/1/2006 If a source deals 3 or more damage to multiple opponents at the same time, this ability will trigger once for each of those opponents. They will each have to discard a card.