Player X brings at least 1 men to location
Disable (type of door) at location
preserve trigger
Player X brings exactly 0 men to location
Enable (type of door) at location
preserver trigger
if this doens't work, i'm going to kill someone. for real
The close door trigger needs to state the conditions for "all players". Other wise in a multi player game one player will open the door and another players will close it and the door will go crazy.