WW Crystal Waltz 20x This attack does 20 damage for each Benched Pokmon (both yours and your opponent's)
WotC does a good job of balancing the price of these decks with the value of the cards inside them
The Amethyst/Steel deck, called Might and Magic, is a showcase for the expansion's new keyword, Resist, as well as the Madam Mim and Merlin package, which is all about bouncing your own characters back to your hand to amplify their effects If you're looking for the starter deck with the more universally useful cards to start building your Rise of the Floodborn collection, you'll probably want to pick up Might and Magic first, as several of its cards will likely see play in the constructed format
Some cards have cost reductions based on the board state or have an alternate ability to use the card in a way that costs a bit less
Dual lands are still great because they can produce two mana colors, and if your deck only runs two or three colors, then chances are itll be able to cast most of the cards in your hand