Ok, I said 'All_creatures' but this is not a valid script command, I was thinking of 'Total_creatures'.
Anyway, I've tested it and 'ALL_PLAYERS' works with the KILL_CREATURES command, 'TOTAL_CREATURES' does not.
Also, there seems to be a bug that it only kills one creature max, I'll report that, but there is a workaround in 'NEXT_COMMAND_REUSABLE'. The problem you will run into is that you cannot count how many creatures all players together have. The command 'IF(ALL_PLAYERS,TOTAL_CREATURES >= 200)' does not mean all players together have 200 creatures, but every player has at least 200 creatures.
What you could do is this:
Code:
IF(PLAYER0,TOTAL_CREATURES >= 50)
NEXT_COMMAND_REUSABLE
KILL_CREATURE(PLAYER0,SKELETON,LEAST_EXPERIENCED,1)
IF(PLAYER0,TOTAL_CREATURES >= 51)
NEXT_COMMAND_REUSABLE
KILL_CREATURE(PLAYER0,VAMPIRE,LEAST_EXPERIENCED,1)
ENDIF
ENDIF
This will kill of the weakest skeleton of the player whenever he gets a 50th creature, and if he runs out of skeletons whenever he gets a 51th creature he will lose his weakest vampire. This only works out well if you don't give the player a torture chamber to convert heroes of course, otherwise you can still convert 100 heroes if you want.
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Edit: Since version 0.4.5.1589 that bug is fixed and it is now possible to kill multiple creatures with one command.