Use global difficulty.

mods/ra/maps/intervention/intervention.lua

@@ -6,6 +6,7 @@
    the License, or (at your option) any later version. For more
    information, see COPYING.
 ]]
+
 BeachheadTrigger =
 {
 	CPos.New(120, 90), CPos.New(120, 89), CPos.New(120, 88), CPos.New(121, 88), CPos.New(122, 88), CPos.New(123, 88), CPos.New(124, 88),
@@ -17,8 +18,6 @@ BeachheadTrigger =
 	CPos.New(137, 104), CPos.New(137, 105), CPos.New(137, 106), CPos.New(136, 106), CPos.New(136, 107)
 }
 
-Difficulty = Map.LobbyOption("difficulty")
-
 if Difficulty == "normal" then
 	BaseRaidInterval = DateTime.Minutes(3)
 	BaseFrontAttackInterval = DateTime.Minutes(3) + DateTime.Seconds(30)