2008-04-01 : Giving a creature flanking after blockers have been declared won’t have any effect. Specifically: — If you give flanking to an attacking creature after blockers have been declared, it’s too late for flanking to trigger. — If you give flanking to a creature that’s blocking an attacking creature with flanking, it’s too late to prevent the blocking creature from getting -1/-1, even if the attacker’s flanking ability hasn’t resolved yet.