Filling a hole; was Runic Iguanar and this appears to quite nicely work with the mythic as being a way to keep playing after all your land goes boom. And, um, desynergises with the white card that blows up mana creatures? Maybe that's deliberate?

Needs P/T.

This looks absolutely nuts. I could imagine whole combo decks be built around this in older formats from modern and beyond. Again, maybe not an issue for its own limited context.

You do have to get it tapped; which then means it's a 2 card combo to reduce costs by 1. Or you can attack with it; which is the intended use - which is why it only has 1 toughness.

It is indeed a very potent upside; but it's not a unique effect. There's a whole cycle of Ruby Medallion already - this is pretty much that effect with a downside.

Except Ruby Medallion doesn't reduce the cost of Shock to which makes it much easier to safely attack with this on turn two (burning away any attacker) and then just play some cantrips with mana cost to cycle through your deck.

That's why Runic Iguanar was actually much closer to the mark.

That's also the difference between affinity on Frogmite and affinity on Somber Hoverguard. If it results in free spells its always more concerning.