IDK why but everytime i use it i feel like it would be a perfect ability for on hit effects. I would be fine with a reduction in Q damage if it meant he could have that for when he goes top lane.
SpiritGear1 voteswould seem like a good idea but adding On hit effects on abilities that could potentially stun (his passive and Q) seems to go over board.
HandheldBrandon1 votesIf Leona's Q can do it then why not Tahms.
Or Renektons W.
Or Udyrs Bear stance.
Only Play Darius1 votesBecause those are all melee range.
Have you not seen the problems 
has been causing solely because of his mystic shot?
HandheldBrandon1 votesAll of them have gap closers to close that range.
Leo has her E which itself is a ministun.
Renekton has the ability to double dash.
Udyr has crazy movespeed and a mini dash in bear form.
Tahm could drop his Q and stun and it would be the same as Leona dropping her E and Q and getting 2 seconds of stun or renekton Double Dashing and getting 1.5 seconds of stun off an empower W. Tahm has none of those things except his ulti which also throws out a giant warning that hes about to do it.