Boost is the new set mechanic that allows a player to put a card from the top of their deck under a character to give them powerful passive abilities
Each booster contains twelve randomized cards: 6 common cards, 3 uncommon cards, 2 rare, super rare, or legendary cards, 1 foil card (random rarity level).
Three underperforming items and actions in the Amber-Amethyst Starter Deck Dinglehopper Part of Your World Hakuna Matata Three underperforming items and actions in the Emerald-Ruby Starter Deck Stampede Steal from the Rich Hes Got a Sword
See the Enchanted rare cards revealed in Ursulas Return i the gallery below
You can cast it as a Force Spike for 2 mana and counter your opponents 2- or 3-mana play, and you can put any amount of mana into it later to counter bigger things
Sure, there are a few problems here and there, but the flavor delivered by Wizards of the Coast is, as per usual, mostly stellar