This is a grueling battle of attrition. Tahm Kench wants to poke you down with Q and win short trades, while you want to scale into your level 9 power spike. He is one of the few tanks that can actually out-duel you early if you aren't careful.

A battle of attrition against a heavy tank. While P gives you the damage to hurt him, E allows him to soak your burst. In the short Mid lane, focus on short trades and using E to stop his W engage.