Here's my alter ego. There's a little tweak, she will level a little different than other monsters, a little weaker than a real panther for fairness but not with my hit die, 1d8 instead.
Oh, Joy wants me to say we have a choice for hitpoints, we can either get full hit die, so Cat would say have 12 HP now, level 2 have instantly 24 etc. or we roll each level up, so she could have as little as 13 if she hit a 1. We both think the former because otherwise we're pretty weak. It's like for veterans otherwise, so she just wanted to dictate maximum HP but thought she should ask at least if you want a harder or easier first time.
