Without going too deep in the top-down design, the Mosswood Dreadknight is the sets take on the Arthurian legend of the Green Knight who, after being decapitated by Sir Gawain, rides away for the two to meet a year later hence the card coming back from the dead after a time
Royal Treatment works against all hostile effects, from "destroy" to -X/-X to getting bounced to the hand, and it even works against the Cursed enchantment role as well
What affects the value of Unstable Mutation
Play Elves, generate mana, and overwhelm your opponents
Endless Atlas gives you constant card draw so long as you have three lands with the same name, War Room lets you pay one life to draw a card, and Minas Tirith draws a card so long as you attacked with at least two creatures
Transforming into Ghost-Spider gives you flying, vigilance, and haste, along with steady counter growth whenever you play from exile