Crowns and Quests adds 12 playable characters with unique abilities, along with Quests that the players must work together to complete while defending the Castle. Quests include searching for evil temples, hunting assassins, destroying magical stones that bring the enemies closer, teleporting the entire Castle to safety, and more.
In Crowns and Quests, each player chooses 1 of 12 characters with special abilities to complete 2 of 18 challenging Quests while defending the Castle. Quests include seeking magical scrolls, getting evacuees to safety, cutting off the Monster army at its source, locking down the frontier of the kingdom, and more.
Note that this expansion is compatible with the 1st edition. It does not add any components that need to be mixed in with the base game components. There will be an aesthetic difference, but not a functional one.