How to double the damage for a skill?

[Bsweest]

I want to make a skill like concentrate(charge) in persona but i can't find a trait that make you multiply the damage except increase your attack. Can some one suggest me any plugin or command can make this work?

 

[AdeptusUK]

Is the issue that you NEED the damage to calculate first and then be doubled or that you need the buff to work for any normal/magic/special attack?