User blog comment:Tridan V2/Kelstor, The Mind-Space Emissary/@comment-24420226-20160109010736/@comment-10768370-20160109135314

He won't have much armor penetration, but the reasoning for it shifting between damage types is, as explained below, that most it is more difficult for AD-heavy champions to build armor as there are relatively little AD-armor items and same for AP. Therefore, if my guess is correct, he won't need a lot of armor penetration as AD-champions generally have little armor.

His E can in theory hit up to 3 times, if you manage to walk in it, out of it and back in it before it collapses which should be possible although I don't understand why anyone would do it. But the collapse would do double base damage as well since the champion already got hit before. So the ability is generally geared towards 2 hits, but could hit 3 times if circumstances allow it. You'll most likely hit only 2 times, so that's what I aimed for in damage though.

And a single spell rotation, if he would still have to stack up his passive, would deal 772  magic damage.

A single spell rotation, if he would already have max stacks on his passive, would deal 864.5  magic damage.

Which is, indeed, not an insane number. But is comparable to some other utility mages like, and. Even though I know his damage is a bit lacking, I generally designed him to lack some damage but bring a lot of utility to the fight. However, I'll up his damage a bit on to make him a bit more dangerous.