It's the same idea that if a surge applies to everyone (not not a new one for each target) then creatures have the ability to cancel it for all. The rules are normally as simple as they can be.
I would question if any creature (hero or monster) can do so if the ability to do says "when the target of an attack". Unless the blast is targeting that creature, I am not sure they get that option. We have come to that point a couple of times. There is different wording for different abilities, letting some creatures to act in this way if they are count in a blast but not in the targeted space.
It's absolutely a question of whether the ability in question uses the wording "targeted" or "affected." For example, the "Heavy Cloak" says: Exhaust this card after dice are rolled to cancel a surge on an attack that targets you.
If we're talking a surge:blast attack (for example,) the cloak can't be used by a figure adjacent to the original target square for two reasons.
1: The cloak specifies that the attack must target you. The wording of blast is that the attack "affects" each figure adjacent to the target space. It does not "target" those spaces (same case with fire breath.)
2. The time to use the cloak is "after dice are rolled" since the attack doesn't blast (or fire breath) until the spend surges step, by the time the attack is affecting nearby figures, dice rolling step of combat has come and gone.
However, this works both ways. The Hybrid Sentinel's "Prey on the Weak" ability does not trigger if only if the "fire breathed" figures have low might. However, if the initial target has a low might, the entire attack gains +1 wound.
On the other hand, the "Cloak of Deception" ability says that if you pass the test "you are not affected by the attack." You could avoid being damaged from either a direct attack, or a blast/fire breath with this gear.
Edited by Zaltyre, 09 June 2014 - 09:31 AM.