who is this item for

Anyone AP who moves a lot or casts a lot to refresh its charges.

I imagine its pretty good on

Still just a luxury item at best though.

pretty much any ap caster who can spam spells or move really fast. so thats most of them

I rush this on diana mid, second item diana jungle

Literally any AP caster that can even moderately spam spells (most of them.) If you can't cast very quickly, or have little use for the movespeed (most AP tanks, think Sejuani, Amumu, and Nautilus), then this item may not be that great.

it sucks

its pretty good on kennen. you can rush in for proc #1, throw a q as youre running around and w for proc number 2 in just a few seconds.

I am building it on Xerath too. Still have to try it on Morde.

I tried it on Cass, and it was quite good. Her AP scales to a pretty high level with her passive, so she gets a bit of extra damage off the proc. Not to mention the fact that she's always casting.

Ever mage with longrange poke or a spamy skillset can make good use off it, and thx to the good base damage you can add it as single off item on some ap-tanks. It isn't a must buy or even rush item on all the listed champs, but they all can use it well.

AP assassins (Kat, Akali), spammy mages (Cass), mages that move around a lot (Ahri, Nidalee) and mages whose waveclear is lacking (item is a godsend on Lux) all seem to like it.

It seems less niche than DFG which is cool, but I'm not sure how essential it is on most of them. Any AP character whose damage is mostly loaded into single target spells seems to be best for it, because it helps a lot with waveclear.