User blog comment:Deshiba/Case study; Mana Regeneration./@comment-4091261-20140920180642

Where mana regen fails, mana alone prevails. If you really want to go spam ham, all you need is a larger mana pool. That's why is still pretty important on. and is kind of iffy. It's great if you can have your ghouls keep attacking, but if the enemies just run away then kinda fails. Without the ghouls, deals more magic damage than physical damage and  is based on physical damage.

All the champions you've listed have as manaless have a restriction. They can't use mana. Therefore any mana item that they could buy is a lot less effective than an item without it. It works of course, but you got to think of how crazy it would be manaless champions would have if they could use items with mana without the cost of mana. sustaining for days with. Then there is jumping on all the adc's because he just got a. Finally there is. Heck people get on manaless champions anyways cause the burst is that good!

It needs to be made clear that the largest benefit that mana champions have is the ability to extend their mana pool. No other kind of resource can extend -or even shorten for rage/flow- their pool to reap the benefits without having to worry about waiting for their bar to fill up.