Magic Door

Doorway in the land of Kolyma with 3 doors built into it, requiring 3 magical keys. Each door contained a riddle pointing to where each key could be found. The doorway is both a passage to the other side of the mountain range for the citizens living in eastern Kolyma if they have the right key, if citizens didn't have the right key they would end up in random locations across the world of Daventry, and use of the 3 magic keys would lead to the enchanted islands where Valanice was held in a Quartz Tower.

Behind the scenes
The Magical Doorway inspired the Door of Destiny in KQ2 (AGDI). Unlike the magical door it was a slab of stone with 3 slots on the surface that required 3 magical stones instead of keys, and it was 'alive' with intelligence of its own.