First, thank you for an awesome mod. I don't usually comment at all, so this is me being invested :)

I have a few suggestions regarding the challenge:
- make the player start as Lilith, so we'd have to rely on the Plushie to deal damage
- remove Conception and Box from Lilith, so it's not too easy
- as a reference to toys being bought in shops, maybe remove the treasure rooms altogether, and fill the store pool with familiars

And now the random idea - I see that a lot of work was put into the gfx as well so you may not like it, but why is the Plushie not a teddy bear? that would be +100 in cuteness and also see pic below :)

https://s-media-cache-ak0.pinimg.com/564x/ac/85/65/ac85657952511bb3b9e3afa879eefcb0.jpg