i always takes about 3-4 people to kill this guy. most tamh kench just build health, no armor or magic resist. yet they are so fucking hard to kill. they get health shield that absorbs like 3k damage. fighting him 1v1 is impossible. he will just repeatedly eat you and use his shield.
what is a good strategy or counter against this troll champ?
and frankly any other % HP damage.
ignore his ass im teamfights until he's the only one left
Poke him down (he won't want to shield so he gets his health back later), stun him, burst him the rest of the way before the stun wears off.
the thing with him is that his shield is only applied to his grey health, and his grey health only lasts a few seconds before it degrades. Sure he gets a small bit of health back but you have to slowly chip it away until he can't make a big shield when you actually initiate for the kill and also, as mentioned above, cc does help. Well heck cc helps kill in any situation.
Another way to go is to try to burst him down with some high damage ability that will do more damage than they expect before they can even CONSIDER using their shield. I think annie or another champ with a good stun-and-burst combo works well here. Get their mildly low with pokes, then apply the stun-and-burst before they can shield. I think a common factor of most tahms is that they're overconfident because of their Q cc, their shield, and their devour which makes them think they can be tanky and burst a fat % max hp chunk of your health off. Use that to your advantage to make them screw their positioning when they're trying to kill you.
Also mentioned above, champs with % health damage. 
or champs with 
that can annoy him.
