Magic: The Gathering Comprehensive Rules Changes - Core Set - Ninth Edition to Ravnica: City of Guilds

Old rule (Core Set - Ninth Edition)	New rule (Ravnica: City of Guilds)
Attacked [Click to view all changes.]
Attacked Some triggered abilities trigger when a player is "attacked." At least one creature must actually be attacking that player for such abilities to trigger. Also, "attacked" means "attacked by one or more creatures," so such abilities can trigger only once each combat phase. See rule 306.3.

Old rule (Core Set - Ninth Edition)

New rule (Ravnica: City of Guilds)

Attacked

Some triggered abilities trigger when a player is "attacked." At least one creature must actually be attacking that player for such abilities to trigger. Also, "attacked" means "attacked by one or more creatures," so such abilities can trigger only once each combat phase. See rule 306.3.