Chroma's page

It seems like a poison build. I'd say it's 15 for initial effect, and 15 each round for 5 rounds. If they succeed in round 2; they'd only take the first. If they succeed in round 3; they only take the two prior. It has the potential to deal 6d3 con, but if a save is made round 3; they'd only take the 2d3.

I think yes, once you inhale it, you make the saves, even if you move away. It's not really "C", as you have a chance to make a save in round 2, 3, 4, and 5. Kind of a/c; if you will. Use it like a poison.

All broken-ness aside: if he's a vetren GM I see one of two scenarios. A) He intneds to throw some hard encounters at you, and expects you'll need the healing. B) That's a cursed artifact that will either take a ton to restore; or have a hidden draw back once finished.

In general, "at will" casting should be avoided for the aformentioned reasons. The AC is kinda huge too, but clerics are capable of wearing full plate; and I'd argue that check penelties are not as important to a cleric in the first place (as say, a rogue).

I would personally have probably done something a little different: probably a lower AC; like 6 or so; and the ability to STORE x number of spell levels in it. I don't have any books in front of me atm, but that would seem more reasonable.

TL:DR; it really depends on how your GM intends this to come into play.