Random gatherer gave me Uktabi Wildcats and Day of Judgment. I found it funny that the Wildcats could survive the Day, by proxying a land instead. This is not that, but it's a bit closer to fair, I suppose.

I don't think this needs to be 8 mana, given the */*. The Wrath cost is very steep (compare with Mageta the Lion) so I think 5 mana would be fine. It's not like this guy actually regenerates very easily!

I wasn't sure where the upper limit of this would be. Magic's power level has changed quite a bit over time, so comparing it to a card like Nightmare or Molimo, Maro-Sorcerer isn't great. I just knew that this card would commonly have a higher power and toughness than whatever you cast him for, so my mind just kept increasing that cost.

Instead of thinking what the card should be costed based on how powerful the abilities, though, I should be thinking "At what tipping point would I be willing to put a card like this in my deck". I'd pay 6, and I'd pass if I had to pay 7. That's probably as good a judgement call I'm going to get.