if you want Drop your suggestions here, it will be passed.
give something new which was not in the editions so far.
That is something attracts his interest.
Tentacle monster pregnancy mechanic.
Have her get impregnated.
Have her slowly start to show.
If he wants to be extra creative, have it change her stats a bit. Moves slower, but has higher magic due to the energy pulsing inside her.
Eventually, she's forced down on her back to give birth.
Monster battle: she has to fight her own tentacle offpsring.
If she loses, the cycle repeats.
If she wins, game continues. Maybe a bonus of the higher magic stays.