By the rules, there is no way for the character on the receiving end of an area-effect attack to avoid the blast. There is a nod in the defense rules, but the rule doesn't explain how to actually defend against something where the character isn't the direct target.
Here, I have created a house rule to address that concern (inspired by Michael Chandra's rule, in
this thread).
Dodging Area-Effect AttacksCharacters may attempt to avoid an area-effect attack by attempting to move away from the epicenter of the blast. This is an Interrupt Action called Move, which costs the character a -5 Initiative Score. The player makes a (Reaction + Intuition + Running) [Physical] test, at a -2 penalty. Each hit enables their character to move either 1 meter (for dwarfs and trolls) or 2 meters (for elves, humans, and orks) away from the epicenter of the blast (as per the rules for Sprinting).
This Interrupt Action counts against the character's total movement for the turn. Also, the character is considered to be running until the end of the Combat Turn, and so incurs the normal penalties and benefits of running. Finally, count this Interrupt Action against the characters maximum number of Sprinting tests for the Combat Turn.
As with any other Interrupt Action, you may combine this Interrupt Action with Full Defense. You still suffer the -2 penalty to the roll.
End Rule TextNotesPractically, this means that characters may be able to get further away from the blast radius of an explosion, and thus take less damage overall, or even escape it entirely. Of course, when it comes to spells, they usually need to escape the area entirely, or else they take the full brunt of the spell.
By the rule text above, a character
must take the -5 Initiative in order to dodge the area-effect attack. If the player is unwilling or unable to make that sacrifice, then their cannot avoid the blast. This is intentional because of the drastic effects that this Interrupt Action has on combat. A generous GM may allow characters to make a standard Reaction + Intuition test, without the -5 Initiative Penalty; all of the other factors, including the -2 penalty to the roll, would still apply.
The rules text does not say what happens if the player fails, glitches, or critically glitches. I am divided on how I would handle this. Here's a few options.
Failure 1: Treat this result as if nothing happened. The character simply didn't have any time to react.
Failure 2: The character still suffers all the benefits and penalties of running and Sprinting, even though they don't actually make any significant movement. This represents the character already being in "run" mode, so to speak; they just haven't gotten anywhere.
Glitch: The character experiences all of the penalties, but none of the benefits.
Critical Glitch: In addition to the results of the glitch, the character, in a blind panic, runs toward the blast. Move the character either 1 meter (for dwarfs and trolls) or 2 meters (for elves, humans, and orks) toward from the epicenter of the blast. If the character is already at the epicenter of the blast, he will be knocked Prone or effectively disarmed (whichever the GM finds more appropriate) in addition to any other effects.