Ondevil2:
atcommand "@cleanmap";
set $@mob,70;
.....
Ondevil3:
atcommand "@cleanmap";
set $@mob,58;
.....
Ondevil4:
atcommand "@cleanmap";
set $@DS_complete,1;
But, if you use above code, when you kill the last monster, the items wil be gone as well because @cleanmap will trigger everytime new monsters are summoned.