Fire and Misdirection

[action5]

I searched the rules forum, but couldn't find the answer to my question:  Can Fire (fire/ice) target multiple things, but deal dmg to only a few of those targets?  Example: my opponent has a 2/2 creature in play, misdirection and a blue card in hand and I want to destroy it using fire.  Can I play fire targeting both my opponent and the creature, so that it cannot be misdirected?  Also, on a related note, do I need to assign damage as the spell is cast, or can i assign damage as the spell resolves?  

Thanks in advance.

[Ephraim]

You can't do this. When dividing something, each target must receive at least one of whatever is being divided.

[lilmidget]

The Comprehensive Rules state:

409.1e If the spell or ability affects several targets in different ways, the player announces how it will affect each target. If the spell or ability requires the player to divide or distribute an effect (such as damage or counters) among one or more targets, or any number of untargeted objects or players, the player announces the division. Each of these targets, objects, or players must receive at least one of whatever is being divided.

So no you can't target your opponent if you hope to kill that creature.

Cards that target must be have their targets announce when you play the spell. Cards like Cunning Wish do not use the word target so you do not have to let your opponent know which card you are choosing until after it resolves.