OK. So here's the challenge:
Fix the Mountain King using a minimum of new models and abilities. Models that you think think we could actually get without being stupidly overpowered as a faction. So the optimal model would be ONE model and ONE ability / Animus, and wouldn't break our faction in half.
SPD6 MAT5 RAT5 DEF13 ARM15 FRY3
2x P+S10 open fist
1x POW10 RNG 10 ROF2 Thorns
When a warjack or warbeast damages Thornspitter Troll with an attack, it suffers d3 damage if Thornspitter Troll is not destroyed or removed from play as a result of the attack.
Uncanny Accuracy: Cost 1, RNG6, Target Model's Ranged Attack Rolls are boosted for this turn.
I think this would be a good start? The Thornspitter Troll would be independently good while not being too crazy awesome that everyone would have to run it in order to win. It makes the Bomber better at close range, but since it competes with Snipe, I don't think it would be required. The Blitzer would love it... Which would be a win in my book - The Blitzer seems like it needs a smidge of help. Uncanny Accuracy would be good on Jarl, but not broken. If we got a 2pt solo that could give Ancillary Attack, the potential for 2x boosted sprays would make a really good combo. At that point, we could have Janissa, KSB, Thornspitter Troll, and Ancillary Man, and we'd be difficult to approach, since the MK could spray one avenue of approach, and wall off the other. If the enemy tried a half-assed assault on TMK, he'd just spawn a lot of whelps.
Comment on my design, or add your own!
Edit: So I feel my design accomplishes not being broken pretty well, would be a useful addition to our faction outside of just buffing the mountain king, and is pretty plausible. What it doesn't do is save the mountain king with only one model. Even with the Thornspitter Troll, only one spray isn't enough to propel the mountain king to greatness.