Ozdec said:
Extra Damage Action (11th level): When you spend an action point to take an extra action, you also add one-half your level to the damage dealt by any of your standard action attacks this turn
...
there is encouragement to spend the AP for the extra action first and then apply the bonus to your normal "Standard Action" as well. The SA's one also applies to any OAs or additional attacks prompted by say a Warlord power

- Nasty
I noticed this too, but there is a potential issue here in that the power can retrospectively affect the outcome of an attack that's already been made
and resolved.
Eg. 1
Warpriest in combat with orc.
Standard action: Warpriest attacks orc 1. Reduces it to 3 hp.
Move action: Warpriest moves to orc 2, taking a OA and 10hp damage from orc 1.
Action Point: Warpriest uses an action point to attack orc 2. As soon as he spends the action point, orc 1 keels over and dies.
Or even worse:
Eg. 2
Warpriest fighting an orc.
Move action: Warpriest moves into melee with orc.
Standard action: Warpriest attacks orc 1. Reduces it to 3 hp.
Action Point: Warpriest uses his action point to take an extra action. Orc keels over. The Warpriest is left with no other targets.
Eg. 3
Warpriest fighting orc.
Standard Action: Warpriest uses Cascade of light. Reduces orc to 10hp. Makes it vulnerable radiant 5.
Action Point: Warpriest does something. Orc takes 5 points of extra damage from the Cascade of Light. The ability is radiant and the ork is now vulnerable 5 to radiant damage so it takes a total of 10 damage. The orc dies.
It can be explained as blood loss, shock, etc but it still seems like a wonky rule to me...