I believe I was over thinking things. The following from the rule book would lead me to believe it's allowed.
To resolve an attack against an enemy, a player follows
these 3 steps, in order. Players may play event cards
and take actions at the end of each step.
1. Declare target of attack, and declare attackers.
A player does this by choosing 1 enemy with whom
he is currently engaged, and exhausting any number of
characters as attackers.
2. Determine attack strength. Add up the total attack
strength of the attacking characters that have been
declared against that target.
3. Determine combat damage. This is done by
subtracting the target enemy’s defense strength
from the combined attack of all the attacking characters.
The remaining value is the amount of damage that is
immediately dealt to the target. If the defense is equal to or
higher than the attack, no damage is dealt.
Specifically, it says you can play event cards and take actions at the end of each step.