In the past, Tahm's W went on CD even if the enemy he targetted died mid devour animation. That bug is now even worse because of how the W identifies allies vs enemies to the full CD or the half CD. If you devour an enemy and that enemy OR minion dies mid-devour animation for any reason, the W cd is 28 seconds, not 14 (even though Tahm targetted an enemy or minion).
Tahm's W works like this. He devours a target, after the target is in his belly for 0.5s, the CD is cut in half. But if he never fully devours the target, that mechanic that distinguishes between an enemy or ally never happens.
This is counterproductive to the aggressive playstyle that you wanted to force on Tahm players when the W was nerfed for allies. We can't even eat enemies without this bug triggering and hitting us with the full 28 second cooldown. Especially since Tahm is 53rd place out of 54 top laners and 20th place out of 30 supports, he doesn't need more bugs (he's 44% win rate now).
1) Gragas Approach - revert CD back to 14-8 seconds and if you devour an ally, you're hit with the penalty CD (14-8 more seconds added on top of the normal CD). Gragas's Body Slam has a similar mechanic where if he hits an enemy, he gets 3 seconds off - thus showing you have the technology to make the opposite, where you add seconds onto the CD, happen.
2) Instead of registering after the devour is complete, register the moment the ability activates. If the ability goes on cooldown, check the status of the last targetted enemy and base the CD timer off of that. Ekko's R has a similar approach in that it tracks where the position of the enemy on the map 4 seconds ago. That already stores a lot of data, even if you only track 0.25s beforehand, so this Tahm tracking system should take much less data.
List of other every Tahm bug to date:
1) Minions die in stomach due to Sunfire or Bami and Tahm doesn't get the projectile + wastes mana.
2) The stacks takes 0.5s to apply, instead of instantly. So many times I apply the third stack and then try to devour and the targetting system chooses a minion instead, and that's because the third stack hasn't registered before I cast W, even though the AA damage has registered. Vayne's and Gnar's 3 stack passives apply instantly so please check this out to see if you could implement this on Tahm.
3) Tahm's R indicator is always green. Even if it's on CD, I've had teammates spam ping my ult because they thought it was up and I was just being a shit top laner :(
Thank you. -tips hat-
For support Kench, a QoL buff would be a "Get out of belly" indicator, just like Kalista has on her ult.