Just how many people aren't aware %health damage counters Tahm?
COUGH
COUGH
%Health damage doesn't care if you have 4000 health. Dealing 10% or more of your health is really dangerous to tanks.
Kindred just auto-attacks you to death whilst dealing 12% of your current health as BONUS DAMAGE at 10 stacks.
Vayne's W at max rank does 12% of your maximum health in damage every 3rd auto-attack.
Volibear's W deals %max health damage and is increased based upon how much health you are missing.
Mundo's Q deals 25% of your current health at max rank.
True
damage
as
well.

Let's not forget the biggest danger to tanks in general:

So stop complaining about Tahm Kench and even Cho'gath being OP. Learn counters to champions for fuck sake.
