Balance suggestions for mod

[TheLoneWonder]

So I'm trying to revive the Charlie character mod for DS singleplayer, since some folks made an updated version for DST. Right now I've set up so that she transforms into her shadow form when below 45% sanity, in that form she'll do higher damage and have vision at night, but only while her sanity remains low. It's all working, but my problem is balancing - I don't want people to exclusively use her shadow form because of the higher damage and night vision. I need to present incentives to use her regular form and deter from always using the shadow form. But right now I'm at a loss for what buffs and debuffs I could give each form.

Any sensible suggestions for how to balance this would be greatly appreciated.

[BraveChicken]

I actually never used the Chariel mod before, so please forgive me if I'll sound like I'm talking nonsense, but how about maybe making the peaceful creatures like pigmen and bunnymen hate her and attack her on sight when she is in that form?
Or maybe making her slowly lose HP while being in it, which also could make players be a lot more careful while handling that form. 
Another idea would be making her unable to eat while being in that state, which would mean that sooner or later they would need to turn back anyways to not starve her to death.

I don't know how helpful those suggestions might be since I don't know much about that mod.
So I'm sorry if that wasn't too helpful ^^;