[HoneyBadger]

Here's my suggestion: Start it with relatively few hp but a high parry, trample size 4, and a decent movement. Have a second form that is immobile and can fire arrows but isn't a construct, again with low hp but higher prot replacing the high parry. And then a third form that is an immobile construct with lots of hp and decent prot, but has no attack.

All forms would be vulnerable to fire.

That would get you a front line of shock troops which would be able to mow down chaff troops, and then provide light missle support and some protection against charges in the form of size 4 barricades.