Would the effect cease after another card of that type was played?
Yes, as the creature gets a partner of its kind. Also, the effect would start if there were many cards of a type but then all but one died.
I like the card. It's basically a shield that doesn't take up the shield slot. Does this stack? Does it effect cards on your side of the field?
The effect doesn't stack with itself.
In the first post, card description. Somehow, many people here can't read. Essence is an exception, and karma+ to him for that.
Yes, what Pilchard said. Type, not element.
As for the side dilemma, I was thinking about (c) when unupgraded and (a) when upgraded. Or just always (a) and cut some cost or add power on upgrade. Both sides' creatures can get insane.
Of course, this would remove the usefulness of the card from your Raynebow and make it useful just in decks where you'll be stocking multiple copies of creatures, but... well, it's sort of the point.
Okay, that is from the discussion, not first post, but... it's one page, you are supposed to read this.