[Clipper]

Door cards are generally one-use only (except for Races, Classes and the like). Keep them in your hand until you are ready to play them, then discard them after playing them. They don't need the "Usable Once Only" phrase and it is often omitted.

You can play it at any time during your own turn. Hence, if you play Find a Map before you Kick Open The Door, you will choose the order of the top three cards, so you will know which Door you will face (and which door you will Loot the Room to if you don't choose a monster). This may determine what card the next player faces too (as it is fairly difficult for them to manipulate the Door deck, unless they are a Cleric). You could also play it after you have Kicked Open the Door and Looted the Room (or between) to better determine what card/s the next player/s will see too. You cannot discard any of the drawn cards, you can only reorder them.