My first instinct was something like a Kobolds of Kher Keep, to combo with Cloudstone Curio, due to him mentioning the combo thing. If not, it will probably have a supertype other than creature, either legendary, snow, enchantment, or artifact. Perhaps an entirely new supertype. As well, a relevant creature type.
An infinite mana cost is combolicious too. It isn't as good as Sneak and Show or anything but you can combo it with Erratic Explosion cards like people did with Draco.
That, and/or it will be an infinity/infinity for infinity mana.
I think I'm more curious now!
http://markrosewater.tumblr.com/post/161878235663/does-the-vanilla-mythic-have-reminder-text
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Numquam evolutioni obstes. Solum conculceris.
Pascite draconem, evolvite aut morimini.
Spells without mana costs can't be played
Same as the one on Evermind
Custom Set
https://docs.google.com/spreadsheets/d/1hu9uNBSUt92PwGhvexYlwFvsh6_SJBlEEIUV3H9_XyU/edit?usp=sharing
Legendary Creature - Squirrel Monk (MR)
9001/9001