I updated the build by the way for anyone who is confused. Heal is no longer a part of the build.

Heal is actually more useful early game when Kassadin is otherwise very fragile (pre-level 6). But also good for a couple baits. Leave yourself at low HP, let them think they have a kill, then heal and burst them down. One time of that can give enough of an advantage at low levels. Ignite helps get another kill too.

I have used heal for many instances where I myself did not need it. An instance that comes to mind was my laning partner with no HP and ignite on him. I was just coming back to the lane after buying boots, and he would have died. I got there just in time to pop heal, which gave him just enough HP to survive the ignite.

You are right, Kassadin does not need heal usually (again, except for low levels), but in my experience it has still been extremely useful.

I'd rather see something NOT heal on here. o.x Heal is pretty terrible in general, and Kass shouldn't need it. I'd recommend teleport if you want to be able to push any lane that isnt attended. Another good option is Flash. I know a lot of people find it excessive, but considering how fast you can drop people, once they percieve you as a threat they will run. having both flash and riftwalk means they don't have that luxury. you flash then riftwalk and are instantly on top of them, able to rape face.