ZenonTheStoic's stance on Tahm's damage

Finally, damage. Tahm has the potential to do an exceptional amount of damage for a tank. Abyssal Voyage’s passive is tuned to be very strong. On any champion who has the tools to get to you and stick to you easily this would almost certainly be problematic. But we cannot look at a mechanic in a vacuum (the poor guy would suffocate). Against most of our roster, Tahm does not have the tools to get to an enemy and stick to them. Nearly every ADC should be able to kite him, anyone with a mobility tool should be able to opt out of fighting him, and so on. We believe that as long as Tahm’s stickiness and catch potential remain as low as they are, it is okay for him to have the damage he does.

source: http://www.newsoflegends.com/index.php/red-posts-0512-plans-for-tahm-kench-and-malzahar-state-of-dragonmaster-swain-and-zeds-chroma-pack-development-of-dragon-trainer-tristana-52429/

See? This is the thought process behind Tahm being allowed to do the damage that he does, and what I've basically been saying for weeks now. If you let him get on to you, he's either a wizard, or you badly positioned, and are now about to be accordingly punished.