Omega-Level Energy Absorption: Modify Vulcan's attack and damage values by +1 for each time he was targeted by a ranged combat attack since your last turn.

Sway, Darwin, Petra: Vulcan can use Incapacitate, Perplex and Quake.

Does Omega-Level Energy Absorption need to be showing on Vulcan's dial when he is attacked to get the modifier?
No. With the way OLEA is worded, it doesn't matter what power is showing on Vulcan's dial when he is attacked; you'll still keep track of how many times he is targeted by a ranged combat attack. Then, if OLEA is on his dial when you attack, you can modify his attack and damage values.