The Midas Door was introduced to Dungeon Keeper in Dungeon Keeper FX 1.2. Instead of taking damage as usual, it instead takes gold, and only takes damage if there is no gold to be taken. It is named after King Midas, who had a legendary ability to turn whatever he touched into gold, which is precisely what the door does, by deducting the gold from its owner's coffers.
The ratio is configurable, but the default is 1 gold per 5 hitpoints. It is not until this cannot be paid that the door takes any actual damage. The Midas Door is a double-edged sword, because it has the potential to be the perfect defence, yet also has the potential to be easily destroyed whilst adding insult to injury by leaving its owner penniless. True to the door's name, you'll need the Midas touch to maintain the door, for a rapid and sustained income is needed when it is under attack, and the heavier the attack is, the faster your gold needs to be replenished. Because of this, it is not the best defensive door when under heavy attack. One use of the Midas Door is to maintain your Training Room's efficiency, as adjacent doors are hit and eventually destroyed.
