Xerath is one of my all time favorite champions. Although the one thing i hate about him is his passive (15% of his AP is converted into armor). It is pretty much useless to a champion like Xerath. Taking the role of high damage artillery, having armor is pretty useless. If you were even able to build enough AP on Xerath (let's say hypothetically 1000 AP), the armor conversion would not be enough (only 150 armor from his passive at 1000 AP).

This new passive will allow Xerath to become a very strong glass cannon artillery unit.
Arcane Power- Every time Xerath cast a spell or basic attacks, he builds stacks of Arcane Power. Once he reaches a certain number, his next basic attack or spell cast deals true damage to the target.

Now giving true damage is quite dangerous as it does make a champion overpowered. this is why i would consider making the stack at which Xerath would have to build up to quite high. something like around 40 or 50. not to mention, as Xerath players spend more skill points into Xerath's other spells, it increase the cap on Arcane power. by doing this it ensures that players aren't going to be able to dominate the lane because of how much damage the champion puts out.

Xerath's passive is actually very strong in the new meta of AD mids, that being said however, an increase in the scaling of the AP>Armor would be greatly appreciated

I like your idea, but I saw one that fits him a lot more, I don't remember where, but it basically said that Xerath deals more damage the father away his target is, so basically like a Nid spear but with all of his spells.

I am defiantly for something that makes him better at sieging, his passive I feel is almost never useful with of course the changes to armor penetration and the black cleaver shred :l

Dude Xerath has a great passive currently.

ONLY 150 ARMOR! THAT'S IT. SO BAD HERP DERP.

Do u realize how much 150 armor is? Its freakin 150 armor, how is that "only" 150 armor? Pssh, my passive is only worth 3 chain vests, so useless. #Sarcasm. This guy. Though I do agree a passive rework is in order.

Only 150 armor for stacking 1000 AP...

Let us know the next time you get his passive to be worth "3 chain vests"

Don't touch my Xerath. =\ Oh, and to quote other people, "don't fix what ain't broke".

(Also, 15% of 600 is 90, which is 2 chain vests worth, and that is fairly doable.)

I dunno, I think any more damage and he would be too OP. I think his passive is fine, but if it were changed I think it should grant sight for one second upon hitting an enemy with an ability. That way you can track down your targets easier from afar.

So a passive that helps him survive his weakest contingency (getting mobbed by physical damage assassins) is somehow bad?