The Mystery Booster 2 Playtest Card Notes section (reproduced here in individual Gatherer rulings) provides guidance for fitting these cards into the existing rules structure
10 Mythical Beasts Mythical Beasts have nothing to do with Gazelle The King Of Mystical Beasts despite their shared name, and are instead a Pendulum deck with some of the best effects for the card type
Secondly she generates an army of flying tokens that will be able to swarm past any would be blockers capable of holding of Oona herself and lastly she will mill their library to nothing in fairly short order allowing her and all her minions to hold back and defend if needed while still working towards a win
Fleet Swallower + Terisian Mindbreaker Most of the cards that mill half of an opponents library are primarily useful alongside Bruvac the Grandiloquent who turns these triggered abilities into whats effectively destroy target player
You cant really blame them, as its a mistake that all TCGs seem to make in their early days Professor Oak, Pot of Greed, anyone
While some cards have no distinction between gameplay and theme, some archetypes have funny ways of standing out as they take the gameplay to a whole new level
