He literally just needs one change:
E - Thick Skin: Active - Tahm Kench converts **60/70/80/90/100%** of his current grey health into a shield which slowly decays over 6 seconds.
The change part is in gold. Right now, his E is too much of a 1 point wonder with enormous strengths, seeing as how with 1 point in it he can basically double his health for 6 seconds in a fight. That is a huge time period to re-up 90% of your health when you are almost dead.
Other than that, I fking love this champ