How about...you can only play a temple that matches your mark or the opponents mark, sounds like a minor nerf.
In addition if FG's got their hands on these it would be pretty beast, and since the laws of elements don't apply to them maybe they can play temples that don't match their marks.
temple upgraded is too powerful. I'm okay with +1/+0 in the upped and nothing buffing critters in the unupped.
temple's ability needs to cost more, like 4 unupped, 3 upped.
temple needs the DAM to every critter to be buffed to 3 when upped.
temple, what's with the gravity quanta effect?
temple, make that cost 3 upped, and can be destroyed.