Thunderhorn is decent, but totally overrated. In half of the factions he is just an inferior Hailstone Golem because it’s so trivial to play around him when his user has no way to alter your minions positioning.
The only factions that can take advantage of him to a good degree are Vanar with Aspect of Shimzar Abyssian with Demonic lure and to a lesser degree Songhai with Juxtaposition.
I don’t see him much in Abyssian decks (maybe like twice as far as i can remember), probably not because he is bad, but because he doesn’t really fit into the current archetypes that are popular.
Same for Songhai, some Midrange Kaleos builds run it but not all and Reva won’t touch it normally.
That leaves Vanar as the most common abuser.
I guess other factions could take advantage of it in theory by running stuff like Magnetize and/or Repulsor beast but quite frankly, he isn’t worth doing that.
I guess an argument could be made that he deters people from playing battlepets but honestly, is that a big deal? How many battlepets were used before UP? 2, Pax and Ooz, that’s it. And i still see the latter being played, i also still use him in my decks, same for pax. Sure you have to be careful about your positioning when using them but that’s easily done.
The comparison with Kron just falls totally flat as far as i am concerned. Kron was literally the best 5 drop in the game in every deck, hell he even kicked Ironcliff out of Lyonar and made Songhai players use him at a time where Midrange Songhai was considered more of a meme than an actual archetype. Thunderhorn is pretty much never seen in Lyonar or Magmar and rarely in Vet. Even out of the 3 factions that can abuse him, 2 don’t run him most of the time.
Regarding the question in how many decks i run him, i can’t really tell out of my head, i have like 50 decks at the moment and if i had to guess probably 8 or so have Thunderhorn.
So yeah, no nerf please, totally not necessary and would most likely kill another innocent card and in this case, also a very interesting one.