gender change serum, race change serum, body type change serum (muscular, normal, loli, big mama), enlargement/reduction serum, breast milk serum, arousal serum, sleep serum, fetish change serum (I don't know, maybe lust will accumulate more with different effects)
can we change the background, now the heroine is in the domain of tentacles (I don't know), you can make a background of space, a background of a robotic laboratory (possibly with thematic manipulators that you can't just buy\choose), perhaps the mouth\stomach of a huge monster, maybe a milk factory, if you have an idea, throw it in too