I see. Well, technically speaking, there is a mod that has been implemented in the main game. Kinda. The one about extracting genes. Which means that it's possible to get a fairy or even a ghost class. So while it is unlikely, it's a good idea to snowball this into something that allows one to create even more classes.
For example, I have noticed that the closest thing to a tank type class is the mule and slave class, as they have the highest amount of health. We need more monster girls who take advantage of their defense/health. Like I can see the Amazon being quite tanky indeed. Or hell, just add a role for the slime girl to have a new type of class. I am thinking goo. It wouldn't even be that hard, either. Just make a slime girl green and add some code to it and there you go. Like you think the slime race would have a *slime* class? Just being sticky. You want to move? Too bad! You got slime on your shoes! If I knew how to mod, I would try to at least implement it to see how it goes.
I actually think the Barbarians have some pretty beefy health statistics, easily topping 75 in Biesboch. I suppose they're moreso a brute than a tank, since they can target the backline, stun, and unleash a heavy hit. The only thing tank about them apart from their monster health pool is their ability to heal a lot of health but bleed in the process.
As for the basic classes, I'm thinking soldier is the closest you're getting to a tank class, with their ability to stack block in the early game.
While it's true that Barbarians are easily one of the best when it comes to offense and having a decent health pool, I am afraid that won't do when it comes to the jellyfish. For you see, when you defeat a jellyfish with one of the jellyfish tokens active, you lose 20 health. And there are four girls. Meaning, at least, you are bound to lose at least 80 health in total. No other monster girl forces you to a grinding halt and makes you either become a tank via breeding or force you to become cautious. When it comes to me, I like the idea of dealing as much damage as possible. And that's just the bare minimum. At higher tiers, you could lose 50 health after one death. You'd think that maybe the creator would make their zapping powers stronger or stun powers last longer, but no, it had to be literal suicide bombers. Keep in mind that a barbarian at level 50 health is 162 at most. So, at lower levels, you are basically fucked even harder. You are bound to lose half your health. But the thing is, these girls do fight back, and so, you end up losing even more health. And you are losing health via using rapture. The strongest attack one could have. And I know, you could just heal, but think about it, the jellyfish girls are the only girls that force you to change tactics to such an insane degree. You would have to make sure your entire team heals up 20 of their health entirely. And these girls will attack, making healing even harder. So unless you have an active self-healer that is also tanky enough to survive an 80 health loss, you are fucked.
Which is why either change the jellyfish tokens where it becomes either that they benefit jellyfish gals or, at the very least, make sure that the token is nerfed enough. At most, you should only lose 20 health from these encounters. And if not, provide a class that acts like a tank class that can shield others and tank the hits. The ability to direct attacks towards one girl.
That's quite the tangent about Jellyfish. Was this discussion not about what works as a tank class?
As for the on death effect, is that not just an empowerment token? Those have since been removed from the game. Even if they still applied, the jellyfish used to be rarely empowered, so it shouldn't be that hard to deal with. Even finding two at once is a rarity, let alone all four. Be sure you have the latest version of the game.