This changes a lot of how drafting feels, because it allows you to cement a specific strategy a little bit earlier on, or just take the two best cards in your first pack and figure it out from there
Completing a dungeon will also allow specific ability text on other cards to be used, with Gloom Stalker and the very meta Dungeon Crawler revealed as two such cards that gain benefits from a completed dungeon - double strike and the option to return to the player's hand from the graveyard respectively
The full text of each room ability is When you move your venture marker into this room, [effect.] As long as a dungeon card is in the command zone, its abilities may trigger
Currently, its unclear how many of these buyers actually exist, as plenty of serialized cards remain unsold
Based on context, there's a chance the term "challenge" is a less confrontational version of battling or attacking an enemy card
The depth of lore that the game is creating, as well as varying opportunities to create strategies in the game, can provide countless hours of enjoyment