Exp

on join:
	set player's level to 30

every second in "X": #musisz wpisać nazwę świata
	loop all players:
		reduce loop-player's level by 1

Proszę, testowane:

on join:
	wait 1 tick
	set the player's level to 30
	loop 30 times:
		remove 1 from the player's level
		wait 1 second
	stop