Times are tough for your Olivia Voldaren. She came down right on schedule on Turn 4, but your opponent immediately stabbed her with , reducing her to a mere 1/1. Fortunately, your opponent has a juicy 1/1 Human token, ripe for the plucking (and the vamping)! You untap and immediately direct your vampire queen towards a tasty snack with her first ability, only to be met with... for X=1, targeting your Olivia! What happens now? Fortunately for Olivia, and unfortunately for 1/1 Human tokens
Two of the more complicated cards from Avacyn Restored are and . When you combine the two, things get downright confusing. The complication comes from confusion about the interaction of replacement and/or prevention effects. The comprehensive rules say this: "If two or more replacement and/or prevention effects are attempting to modify the way an event affects an object or player, the affected object’s controller (or its owner if it has no controller) or the affected player chooses one to
is a card that suffers from "wall of text" syndrome. It does a few different things all at the same time, so it's easy to get confused. The most important thing to remember is that Divine Deflection requires you to choose only one target. Don't choose your own creature! (Unless you want it to die). The target chosen for Divine Deflection is where the damage will be dealt. You decide what damage will be prevented when that damage happens later. This damage can even be from multiple sources!
With the new card , the wording can be a little misleading. While one might read it to mean that it prevents X damage to you AND X damage for each creature or planeswalker you control, then deals all that combined damage to whatever you targeted, it doesn't quite work like that. When you cast Divine Deflection, you choose a single target, which is what any prevented damage will then be dealt to. This sets up a "shield" for the next X damage that would be dealt to you and/or permanents you control.