I'm having a lot of trouble trying to beat the Inventor.
I know you have to DPS his pylons down to build towers, the problem though is that he keeps chain stunning my units and he has something like 5 free moves at a time.

I tried using wards and they get lost too quickly, I tried using mummy to cleanse and that doesn't work, skeletons are immune to stun but don't deal enough damage, bounty hunter is too fragile, and so on.

Do you have to be at a certain level to beat him? My minions are at most level 10.

It's really unlucky when that blasted inventor spawns multiple stunner pylons and they go straight for your minions, but you can still overcome it with raw power.

First, your minion levels seem a bit low for this point, my best results come from focusing on only 1 or 2 full squads (1 geared toward sanity attacks, one toward physical attacks), so you may be spreading the wealth among too many minions.

Second, big physical damage attacks will let you bring down at least 1 if not 2 pylons per round assuming no bad luck. I like the Werewolf for the extra attack per round with ultimate move, Bride of Iratus for critical hit against all targets with ultimate move, Unfrozen can protect a minion for a turn and hit pretty hard, and Skeleton is actually pretty good for re-directing attacks (from the Werewolf for instance) to itself while avoiding the stun (try to build up it's armor and resistance to make this more effective).

Third, don't neglect Iratus, there are attack spells or items that enable spells that can help here.

Blast those pylons relentlessly and don't give up! Good luck.

Thank you for the advice.
I finally beat him, but only because the AI derped out and stopped summoning 2 pylons at a time followed by lightning.

I had to retreat several times and make new minions with higher level brains I had lying around, but the comp I used was Lost Soul, Werewolf with that mana regen item, ghoul with misericord and a bone golem.

Werewolf would regen mana and pop new moon, mana was used to strip wards, ghoul was used to strip wards and the golem and soul was used to provide wards. Lost Soul also stripped buffs.

What a terrible bossfight, you pretty much have to cheese it to win. On More Pain its not so bad but on GAW its just tedious and frustrating. It's way too dependent on RNG.

Do you really just have to use one or two squads? Is this not like, well, every other tactics game where you have to rotate your recruits to spread exp around?

Glad to hear you won the battle, as you are probably already aware, there are tougher ones in-store (I only just won the final battle of Wrath of the Necromancer on 'Good always wins' just a few minutes ago with only my Banshee surviving!).

That inventor is a nasty boss since stress attacks (my preferred method) just do not work well enough against the regeneration. As you said, it relies on luck with which pylons spawn, though I'm not sure the alternative boss from the DLC is any better (2 Dwarves in steam-powered battle armor). It really does take some luck, also, I just remembered the Zombie helped me on that one with its ability to ignore armor/resistance, but the Werewolf is a nightmare in the best possible way once you can protect it with wards/block; its tremendous damage output combined with regeneration is great.

To your last point, yes, you really only need one or two squads (although more is more fun as greater variety adds more interest). Since you don't need to relieve stress for your crew like in some other games (Darkest Dungeon and so on), you can keep hammering away with the same ones if you choose to do so. For me, once I find something that works I ride it for awhile especially against tough enemies. Whichever way you prefer to go is the way to go.

In fact, the game I just finished I went nearly the whole game with 1 primary squad of Banshee, Infested, Fallen Dhampir/Mummy, and Abomination/Dark Knight (I traded the front 2 ranks as needed). I find using fewer minions leaves parts free for calcination and distillation Alchemy and replacing lost minions. For my experience, the extra levels you gain by using fewer minions really helps out a lot against the toughest enemies. My minions were up to around level 68-72 when I hit the last battle. That was an interesting, rough one.

Is the final boss of the Wrath expansion that much harder?
I just beat the Magister with no casualties. The Gunner that spawned with him was more of a threat.

Well, I never had much trouble with the Grand Magister either, but I found the 'Ultimate Final Boss' pretty tough. To be fair, this was my first and, as of this message, only encounter with so maybe I just had bad strategy. I'll post details below if you want them.

SPOILER ALERT (details about DLC Boss to follow):














It's the Four Great Heroes, they have a shared health/sanity of 4000/4000 so they cannot be individually defeated, each comes with its own wards/blocks, they each get 2 attacks per round, one attacks every time a minion changes ranks, one attacks every time Iratus casts a spell, one always counterattacks when targeted, and the last buffs accuracy and damage for all continuously. I might have mixed up a detail or two or forgotten something. I was able to drive down sanity to 0 and cause heart attack, but I had a hard time.

Yeah, I just beat the four heroes too.
They're pretty tough, but overall fair. I had a much harder time with the Bounty Hunter and the Inventor because of how poorly designed and RNG heavy they are.