Heimer is so powerful, now he wont die!!

Lifesteal veigar

Because having to go back and heal takes away from his average penta kills per game.

AP Ashe

Your ult will deal tons of damage.

Jungler Vayne

Wait for an enemy standing near a wall while ganking, Final Hour, Tumble, Condemn, AAs. Profit!

But what about AP Hecarim?

Super Ult, and you sustain for days.

AD Singed

His ult ups his attack damage, plus, super fast bruiser with a fling? GG

Jungle Cassiopia.

Her W and R slow, so you'll be performing good ganks.

AD Nunu.

He's a yeti and he's tanky, so why doesn't he fight on the front line?

Magic resist Rammus.

Already a tank. Can be very good when the enemy has lots of AP.

Zilean with 6 phantom dancers

You can't kill what you can't catch and all that movement couldn't POSSIBLY be restricted by things like diminishing returns once you factor in his speed buff.

AP Tryndamere