Is it of use to take the defense-skill if my chosen minion allready has 2.5% damage received?
not really, itll help a litte but not much so I'd replace it with something youre not using, what are the skills you usually use?
There actually is. Eventually you break the 2.5% damage reduction barrier, and so you can get like 0.0001 damage
When does that start to happen?
