I'd honestly change the first ability to something more interactive, like an attack trigger. Make his reckless combattery inspire the mercs with Vanishing around him to stick around:
"Whenever ~ attacks, choose any number of creatures you control with counters on them, then give each another counter of a kind already there."
Or something like that. Attack trigger Proliferate, basically.
I'm honestly not sure I like gold tokens in blue, since blue can make mana, but usually only for artifacts and maybe creature abilities at most. Card seems balanced otherwise though. I think it'd be a better red card with a loot into two Gold tokens, but that's just me.
The counter ability is too good; it is a super cheap counter that will hit 90% of what gets played, easily. It doesn't even require a tap.
>spellshaper
My nigga. Seems pretty okay to me, but 3 damage on demand might be a bit much, even at 3 mana. It depends on the environment it's in, really.
Not really a fan of super-expensive PWs, or Nicol Bolas, but this seems like something he'd do/be. I dunno about becoming a creature though; I feel like "going Gideon" isn't something he'd do since it'd kinda be a step backwards to before his spark ignited, and I can't see him relishing that idea.
I agree with the other user; some of these are very underwhelming. Alheim is okay, but could probably also grant trample. Sungrove is way overcosted; I think you could to three tokens for 8 here. Willbrine could do two counters without too much worry, I think, and Vongas is just... really disappointing. Add some life loss or something maybe? Sidron is actually pretty good, to be honest. Good way to end the game some of the time, and vicious against token strategies, which BR should be hating on anyway.