This coming meta will drive casual players from pvp, leaving only krakens...great "adjustment"/"balancing", Plarium.  <slow golf clap>

How far down into gold/silver tiers this will pervade remains to be seen, but I don't believe this adjustment will be looked upon favorably.

I think you are overreacting.

His A1 is a solid Mercurial Counter, but the rest of his kit is weak sauce for PVP.  I will probably do the fusion, but I don't anticipate building him for PVP.  

The Whales already have a vastly superior Mercurial Counter in the form of Sabrael: she has 2 Double Hit AoEs on both of her forms. Additionally, in Base Form she adds lockout, and in Alt Form, she nukes.

Theimios is a Mercurial Counter for the masses.  The Krakens aren't gonna bother with him, but you can use him against them.  

I hope I am...

Or you could put a provoke set on ukko and get close to the same result :P

Use ambassador Lethalin (epic high elf) to put taunt on wixwell and he can keep a whole team locked down with provoke (hmm, I should build that)

I think he'll be good but not great in PvP.

I mean, even if everybody did start using Thermos™: the everdrink for arena, all you need is one cleanse/block debuff champ like elva/pythion/kaja/ankora in stoneskin to nullify him, add on wand of reflection and sheep  and Thermos is screwed

Bot necrod this post but anecdotally I haven't seen this guy once in arena still. 

I have seen him only one time in LA.  I don't use Mercurial so he is a wasted pick against me.  

Still feel like theres just way better choices than him. 

Well, honest mistake.  Seemed better than he is. 😜

No harm no foul.  Ive seen plenty of champs that look amazing on paper and for some reason just dont break into the meta.