Ruby cards have an aggressive approach to their playstyle, with abilities and effects that focus on boosting Strength or Willpower for Challenges against other Glimmers or giving the player extra Lore tokens from making Challenges and winning them
Players play and activate cards in order to gain the lore needed to propel them toward victory, challenge their opponents characters to slow their progress and use other abilities, usually by paying ink from their inkwell
Amethyst decks now have an extra, better top-deck game-winner outside of Merlin Goat
The sooner you can get Gadget Hackwrench, Brilliant Boson in play, the better , since it will reduce the cost of all your Inventor characters and allow you to out-value the opponent on the board
Basically, players can sacrifice the card to grant indestructible to an allied creature along with a piece of equipment Zack Fair once used