Keys are dropped by Dungeon Constructors, which have 100 HP ( x50), and can be used to open doors in the Arcana Dungeon, which hold many secrets.
You cannot mine anything in the Arcana Dungeon except ores.
The recipe for the Arcana Portal Frame is as follows:
It is important that the portal frames be placed in a certain way. First, face westwards (check in F3). Then, step onto the tile in the middle of where you'd like your portal to be. From this tile, place all of the portal blocks, ensuring that the rightmost frame block in the west side is placed last. If done correctly, the portal will light automatically.
What to do here
- Kill some enemies; they drop collector fragments and you need at least 16.
- Find Lord Vatticus and trade some of your collectors for Charged Collectors (16 fragments to 1 Charged one).
- Right-click a Dramix Altar with a Charged Collector to spawn a Dungeon Constructor (You don't lose any charged collectors). Kill these to get different Keys.
- Unlock different doors with the Keys to get to Arcana Ore and extract the Arcaniumwith Charged Collectors.
- Trade Arcanium with different traders (Captain Merik will give you a Wizard's book if you give him 2).
- (Optional) Use a Wizard's Book on a Dramix Altar or Phoenix Altar to spawn a boss that drops Dungeon Tokens, which can be traded to Captain Merik for better items.