Spell binder could be great, but....
The item forces you to wait after everyone uses their spells in a team fight in order to make decent use of it. By then it could be too late.
The only other way is to charge it in one team fight, and then use it in the next. All of this work for 4 seconds of additional AP/movespeed.
Otherwise you stack it on your own while farming which can take a long time.
The point is, this item is a pain in the ass to stack and make decent use of it.
