I decided to spend an hour seeing if I could make Xerath better without changing much about him. Here's what I ended up with.
Xerath was billed to us as an "Artillery Mage", but we ended up with a mediocre kit that screams "doesn't know where it wants to be". Xerath at present suffers from too much setup for too little reward and lack of his own niche aside from Lightning Bolts galore (and not being Ryze). The big damage we want him to do, as most "Artillery" things tend to do is lost on meh scaling and diminishing returns.
Addendum: After reading all the feedback I've decided to try my hand at an entire ability overhaul, keeping the 'slight' changes and the 'vast' changes seperate, while both of which share/keep the sentiment that Xerath needs to be altered.
His stats, quotes, triva, etc? Remain the same.
- Passive reworked entirely, making the old W baseline
- Q gained a .1 bonus to AP scaling.
- W reworked entirely, working like Nautilus's Depth Charge. (Now without MS)
- Added W's old Magic Pen to his R as a passive.
- R remains unchanged due to it being a 3-combo version of other, slightly weaker version of other champion's ults on longer cooldowns (such as Fiddlestick's Crowstorm or Anivia's Blizzard). A change that has been suggested (and would be applied without saying) is smart-casting/normal casting his ult while his passive his in effect (old Locus of Power) and you target outside of your current range, it will hit the max range. This working like Jarvan's flag or many other champions that went through such QoL changes.
- Improved E's range.