What's halfway between llanowar elves and a signet? Has this been made yet? It may be too good in that it's free the turn you cast it, yet comparable to memnite in that maybe the effect is simple enough to be free. Obviously useful in metalcraft/affinity decks. Not sure how good mana acceleration non-green should get... :)

Hmmmm. Interesting. I definitely do think of this effect as costing , although you get a benefit; e.g. Mind Stone or Everflowing Chalice. I don't think being free the turn you cast it is necessarily a problem. It certainly is plausible that this is printable, though.