Demon Form cancel

So, the tooltip reads that Demon Form cancels upon going down to 1 hp. But it also cancels if you cast something that isn't a spell. Fair enough.

I found that if you cast Contagion, which is a spell, it also cancels Demon Form.


EDIT: Profane Ritual also cancels it.
EDIT 2: Firebolt also cancels it.

Similar issue as well.

Spells that cancel demon form for me:
* Essence Drain
* Profane Ritual

Spells that do NOT cancel demon form:
* Contagion
* Bone Cage

I've tested without any support gems socketed, on a character level 23.

Edit:
I suspect demon form does not take into account your weapons and thus, if you need the attributes from your weapon to meet the stats requirement of your spell skill, it will cancel demon form.

Edit:
Indeed "while you are shapeshifted, your weapon slots are disabled", "using a skill that is not compatible with your shapeshifted form [including missing int/dex/str] will automatically revert you to human form"