The slime demon leaves a trail of slime whenever it moves. If anyone steps into the slime it's removed and it affects them: Hunters must survive a weak attack, the slime demon is healed. Tactical rolling around in the poison to stop it recovering is encouraged.
It's behaviour is very different in that it lacks the ability to disengage to the other side of the battlefield or spit out enough fire to cover half of the board. Instead it can drag opponents towards it with its prehensile tongue and has a seriously mean left hook that's capable of flooring even the toughest hunters. However it has a blind spot at the front right, which it cannot reach with its more dangerous attacks.
It certainly feels different to play against, but just as threatening. I'm pretty pleased with how it's shaping up.
I've also added the quality "defended [body parts]" which has the effect of applying a stacking -1 to hit for each of those body parts still intact. This feels a bit more realistic than "You can't hit its body because it's still got an arm" and adds a new dimension in that if the player's losing they can shoot the moon and aim for the head anyway rather than being consigned to a hopeless position.
I feel like I'm fast approaching the point that it's worth codifying the rules and getting some feedback on the core gameplay. At the moment some of them are written down, but others exist only in my head and some edge case conflicts go entirely unresolved. I think that will make a good next step for the project.