A Magical Puzzle Key for opening a door. Innocuous, somewhat simple, but fun to solve, if you like puzzles.
A magical barrier of acid blocks your path. Solve the puzzle to unlock the door.
A combination lock, possibly to open a chest or door or other entry point. A magical puzzle, for those interested.
Checkerboards on floors of dungeons… is there any greater bane to adventurers?
It is said that though the crown has always been passed through inheritance, no man may rule without the approval of the Archmage and the Guildmaster. (Interpretation I leave to interested parties.