Human Form and non-humanoid creatures

[Praxidicae]

I'm currently working up an npc creature borrowed from Harry Connolly's "A Game of Cages" (Which I can heartily recommend to anyone who hasn't read it or it's prequel "Child of Fire").
The creature is the "Sapphire Dog", the McGuffin and supernatural villain of the book. An intelligent Lovecraftian being with a lamprey mouth and scaled polyped skin, that exudes a persistant aura of love, anyone without supernatural protection who sees it is effected and becomes obsessed with being the dog's sole provider and carer, to the extent of killing anyone they see as a threat to this goal, as soon as they leave the dog's presence the aura will dissipate and the victim will be able to act as normal.
The creature can feed those who touch it, permanantly draining them of emotional capacity until they become its devoted puppets (the book describes them as it's "Pets").

One of the secondary abilities the creature uses fairly often throughout the book is the ability assume the form of an ordinary looking (but still blue) dog.

I had considered some form of Glamor or illusion for this but wondered if this ability could be mimicked via the Human Form power (my only concern is that the power by it's very description allows the assumption of a mundane human form.)

[Tedronai]

I see no balance concerns, here.

[Sanctaphrax]

Human Form ought to work just fine for this.

PS: Are you looking for a custom power to represent its mental effects? Because I might have one for you.

[Becq]

I think that the spirit of the Human Form is that while it's active, you become mundane.  So long as that is maintained, it doesn't seem like substituting for an alternate (but still mundane) form would be a problem.  Though the fact that the form is blue (and therefore unnatural) does void an indirect benefit of Human Form -- that is that you appear mundane.

Note that if you wanted to retain the creature's powers while in the alternate form, you could use Human Guise, instead.

[Praxidicae]

Thanks for the feedback guys, looking at it think that Human Guise would be the better choice for what I'm looking for.

@Sanctaphrax: Please do post the custom power, i've been struggling to work out the best way to make a persistant incite emotion aura that makes the dog the target of the affected's emotions. As I understand it, incite emotion can make a victim feel a specific emotion, but cannot directly influence how that emotion is targetted (ie. you could make a person feel enraged but couldn't direct whoor what they vent that rage on).