3+ save with 16 wounds & another 4+ ward save is indeed kinda really OP.
4/6th of all wounds are saved, half of those are warded, so it requires 48 normal wounds, or 32 mortal wounds, to kill.
He also puts out 2D6 ranged attacks for 2 damage that are 3 on a 5 or higher with 3+/3+ which should put out eh, somewhere around 10 wounds.
Monstrous bulk: 4 attacks D6 damage 3+/3+, that's about 6 wounds.
Thunderous twin tailed: two attacks D3 3+/4+ that's about 1.3 wounds.
Maw: 1 attack 2+ 2+ 5 damage, that's 3.5 wounds (when at full health)
For a total of about 20 wounds per turn, not taking into account his rend ignoring most defenses.
Also, once killed it explodes on top of what's around it.
It'l basicly outduel anything it faces and can only really be taken down by concentrated effort of multiple units working together, preferabl from ranged.
He migh be a wee bit OP and can least easily go toe to toe with the likes of Archeon and other silly characters
Also, the golemn is a snake with razor teeth? That's, eh a tad odd, but fair enough, had imagined something else.
As for the skirmishers:
Literall the first line in the ancient time bit:
"In ancient and medieval warfare, skirmishers typically carried
bows,
javelins,
slings",
And past ancient warfare you get the rise of the gun with virtually everyone using ranged weapons.
How does that make my claim that skirmishers
usually employed some form of easy to carry ranged weapon factually untrue?
As for my additional rule; I'd like there to be some sort of benefit to mixing the two, beyond just the benefit of having more potential types of units, though it's not strictly necesary.