RangerWickett said:So what you're saying is, I should ready an action to move when the fireball explodes. That way my movement occurs just before the fireball can hurt me. Ah, good. Thank you!
But that won't work.
You ready based on an action that triggers, not on a condition or effect.
A fireball exploding is not an action. A wizard casting a spell is an action, a wizard using a wand is an action, etc.
This is like saying that you want to take your readied action prior to the damge being dealt by the sword that is hitting you instead of when the opponet attacks - which has the readied action go off just before the attack (and interupts it).
There are some "special" things that will allow you to use a readied action (or equivalent) for when recieving damage - but those are unique and specifically spelled out in the action that they pertain too. It is not a general rule.
IMO you should be able to ready a move for when the wizard casts a spell. So when he starts to cast his spell you can indeed move. You can not however move after he has cast and before the result is ejudicated.
As Hyp pointed out though, all effects and details of a spell are resolved when the spell comes into effect - not when it is cast. This will in general keep you from being able to sidestep a spell per the RAW.