I haven’t had a great deal of luck using Gore Gruntas in single units of 3, lately. That said, you’re right about them offering the Maw Krusha some support with their greater movement. I might substitute one of the Brute units with some Gore Gruntas, as you’ve suggested, for the improved movement and support option.
We’re using the realm spells for Aqshy in the campaign so I thought the Balewind Vortex would be a good choice to increase the spell output on one of the shamans. With respect to being locked in place my thought is to move the shamans up with a block of units using buffs like inferno blades or stoke rage. Then, when they’re close enough to start slinging some offensive spells too, I’ll use the Vortex on one of them for the extra spell.
Just read up on Mork’s Mighty Mushroom. Potentially very nasty!