the summon familiar spell creates a little pet which can cast the same spells as your soverign, and seems fun to have around
however in practise, it's not. in fact it's an extremely frustrating piece of deadweight you have to lug around until you finally give up and let it die.
It has 8 HP, and only gains 2 per level. it has no defense, no dodge, and Not Enough initiative. Also it counts as a unit, not a champion. Which severely limits the buff spells you can cast on it. Most notably, it's barred from Stoneskin and Courage, two spells which might have been able to make it useful.
These facts are compounded by the battle system not allowing us to choose formations or deploy units. in combat the familiar always seems to get placed somewhere around mid-front.
And lastly, enemies always seem to gang up on the weakest target and try to eliminate it quickly.
So as a result? first turn of battle, every enemy focuses the familiar, and it almost certainly dies. Unless you get some lucky misses or an occasional nice deployed formation that shields it. or some low enemy damage rolls. Trying to keep the thing alive becomes a tiresome exercise in save scumming and luck. IF it DOES manage to survive the first round of combat, and actually live long enough to get a turn, then it has to spend that turn running away and casting heal on itself, in which case it's still not being useful to an army.
Put simply, it's too vulnerable, too fragile, and the player's hands are apparently deliberately tied with regards to any way of mitigating that problem. The only real way you can make it tougher is by slowly grinding it up a few levels against bandits and other assorted weak enemies.
I did notice, to my pleasant surprise, that Legendary Heroes now gives familiars 50% damage reduction against physical attacks. And this is nice. it shows that you guys are at least aware of the problem, i think. but it really doesn't go far enough. Doubling almost nothing is still almost nothing. needs moar tankiness