The Lantern Key

Return 100 Gold or fight for the key

Returning the key pays 100 Gold immediately. Keeping it requires a fight against the Mysterious Knight and adds Lantern Key to the deck. The decision includes that combat’s damage and potion cost before any later reward arrives.

The Knight uses Plating and substantial attacks. A deck that barely survived the previous room should compare the guaranteed Gold with the resources needed for another demanding fight. The Gold can fund the first ordinary removal at Ascension 6; it is not merely a smaller version of the key reward.

Carry the key into Act 3

Lantern Key is an Unplayable Quest card that unlocks a special event in the next act. Carrying it occupies a draw without directly attacking or defending. The eventual reward must justify both the Knight fight and the period spent with that card in the deck.

At War Historian, Repy, the key can open the cage for History Course or open the chest for two random relics and two random potions. Those are distinct rewards: a known repeating effect versus a larger collection of uncertain results.

Plan around History Course

History Course plays a copy of the last Attack or Skill at the start of the next turn. A deck with a particularly useful repeatable attack or defensive Skill can choose its final eligible play to improve the next opening. Ending on a weak filler card can waste that control.

If the deck has no useful plan for the copy, the chest’s additional relics and potions may fit its immediate needs better. Inspect potion capacity before valuing both consumables as fully usable. The key belongs to this event chain; it is not the original game’s route to the Heart.