It works.

Code (Text):

1.  
2. on load:
3.     loop 5 times:
4.         if {spawn.dungeon%loop-number%} is set:
5.             add {spawn.dungeon%loop-number%} to {dungeonlist::*}
6. on unload:
7.     delete {dungeonlist::*}
8.  
9. on rightclick on black concrete:
10.     set {_dungeontp} to a random element out of {dungeonlist::*}
11.     teleport player to {_dungeontp}
12.     stop
13.  
14. command /setdungeon [<int>] [<text>]:
15.     permission message: &cNo permissions.
16.     permission: rank.admin
17.     usage: /setdungeon <number>
18.     aliases: sd
19.     executable by: players
20.     trigger:
21.         if arg-1 is set:
22.             if arg-2 is not set:
23.                 set {spawn.dungeon%arg-1%} to player's location
24.                 send "&aSpawn for dungeon %arg-1% set!"
25.                 stop
26.             else:
27.                 stop
28.         else:
29.             send "&cUsage: /setdungeon <number>"
30.