Lets say I have a base damage of 100 and skill that does double damage and another skill that does +5 damage. What would you expect?
205 damage
47%
210 damage
53%
Poll ended at .

@grumpygamer
As a player I want *more* so I'd expect/hope for the second thing. But that can easily become unbalanced.

So I would make it clear to the player: say that the skill does "2 * base damage" or "2 * total damage", depending on which you choose.