Is it just me or is Tahm really strong?

I'm sorry, I just have to rant.

His passive, good idea. I like it. Although, the stacks shouldn't decay, they should be just taken off. Braum's and velkoz's passives don't decay, they fall off. So why does someone who has no troubles sticking to people get to have a decay stack passive?

I don't have a problem with his q, it's a skill shot, it's not point and click or point and win, it's a pretty standard ability. Although sometimes it seems like the hit box doesn't match the indicator.

His w is probably one of the most useful skills in the game, without the damage on it. And it's % max health damage. With 20% at level 1. What? even at high amounts of magic resist, say, 100. Somehow at level 1. That w will still do 10% of your max health if he gets you with it. This ability alone seems like it would qualify for an ult. It is essentially Cho Gath's ult with some minor tweaks and more utility.

E makes me sad. You essentially get punished for doing well against him. In lane, it's not a big deal, slow poke, let the grey health disappear. It's not bad then. But then here comes the team fight section. He easily wrecks a team with his other abilities. Why does he essentially get two health bars during a team fight?

The ult is Tf's ult, just instead of revealing champions you can bring an ally with you. No problems here.

So why is this a thing? Why hasn't it been nerfed? What am I missing? The idea behind him is an AMAZING one, but his stats and skills are just nasty. W shouldn't do damage, or it should to allies as well, making it so that you have to really decide if you want to use that skill. (although damage to allies is a bad idea, it gets trolly).