One wave: entries spawn spread evenly across duration seconds, starting delay seconds after the spawner itself starts (not after the previous wave ends - waves may overlap, which is exactly what a game escalating toward a boss often wants).
entries
duration
delay
Optional
spread entries across this many seconds; 0 (the default) spawns them all at once
One wave:
entriesspawn spread evenly acrossdurationseconds, startingdelayseconds after the spawner itself starts (not after the previous wave ends - waves may overlap, which is exactly what a game escalating toward a boss often wants).