I played morningtide's light, which is supposed to prevent all damage to you until your next turn, but in the match I was just in it didn't prevent any damage, his creatures had protection from white on their turn after playing it, but not when it was played. To my understanding protection from white wouldn't stop the damage prevention, because it isn't targeting anything, but I just lost a ranked match, because the damage prevention didn't work. I don't know if this is a bug or a rules misunderstanding but it needs to be looked into.