I will quote the relevant third part about the playtesting: Step Three: Full-Time Playtesting At Creatures, theres a special room dedicated to testing the card game
I hope this article has helped you figure out whats worth playing
Until the end of your next turn, you may play that card, and you may spend mana as though it were mana of any color to cast it
It retains Claw Slash from its Charizard V form, though now with an added 20 damage
Not to be outdone, Fallen Empires added Goblin Warrens and Orgg, while Atog returned to print for the first time since Revised
Its a small but meaningful spell that pairs nicely with commanders like Niv-Mizzet, Parun and Narset, Enlightened Exile