I am trying to build a power where the character attacks a target normally, but the damage from the attack does not effect the target until a specified event occurs. The power itself is an EGO and PRE Drain that is modified to function as a Mental Attack. The concept is a power for a vigilante who wants to target and attack an unsuspecting evildoer without a direct confrontation. Then, the next time the evildoer falls asleep, he suffers from horrifying nightmares that sap his willpower and courage and weaken his resistance to further mental or presence attacks.
I've looked at Damage Over Time, Delayed Effect, and Trigger, but none of them really match up with the concept. Does anyone have any suggestions as to what may work? Or would it be better to get with the GM and work out a homebrew solution?