So Monster Creation is basically just taking material from a phantasmal species - not being euphemistic here, anything like claws, hair scales, blood etc as long as it's a significant part and has some mystical meaning - and then using magecraft nonsense to grow a big monster in a test tube, just using her reputation as 'someone who makes monsters' rather than physically recreating a monster pregnancy. Obviously that's something that's best avoided and Servants can't really get pregnant in any case. The resulting monster would probably have a power level based on GM-fiat, based on level of materials, etc, but would cap out at just being a really strong monster familiar. It's something that makes sense to put into whatever limit of once per singularity or even once every two or three feels appropriate, along with other restrictions of like, no dragons, etc.

The Noble Phantasm basically has three effects. Reduced damage from physical attacks from phantasmal species, which is pretty self explanatory. The friendliness thing is basically just akin to the D&D/Pathfinder stuff where these things will be one level of friendlier by default but that's not enough that they'll actively help out or not fight back if they get attacked. And if they have a master who's already commanding them to attack it's not like it'd bypass that or anything. Mana tuning basically just means synchronising mana, basically buffing each other by being in tune, but mostly to the extent of increasing output and alignment. Basically the whole being more than the sum of its parts. There's no real benefit to it if there isn't a target who's already friendly. 

I could swap them around as skill/Noble Phantasm if you want. They feel the right way round to me, though, since Monster Creation is limited by time and resources similar to Item Creation and is an actively used skill, and while the Noble Phantasm's passive, it still feels like the more mythologically definitive thing, is connected to a physical object in myth, and would be a bit too complex for a skill. 

Anyway, when it comes to the matter of, uh, bestiality, it's more of just an unfortunate and shameful curse from her past that forms some of the basis of her legend than like, something she'd actively be doing during the rp under any circumstances. I guess I should have made that a little clearer. 

I only didn't put Divinity on there since Circe doesn't have it and they're sisters. Dunno why Circe doesn't have it honestly but it's kind of a do-nothing skill anyway.