The solution to this complicated. You won't actually use a monstermaker for your first wave, have your real monsters kept in a separate place and teleport them in. That gives you the ability to use their trigger condition...except you can't use the trigger condition to target a multisource. (I told you the solution was complicated) So you have to make each trigger condition target a hidden button that targets a multisource. When all the monsters from the first wave have died, all the hidden buttons have been targetted and the multisource targets your second wave monstermaker. Take a look at the rmf for LDSF in the Laser fun competition. The grunts are teleported in; when you have killed all the grunts (in any order) the ending sequence is triggered.