(This does not work with xmlSpawners. I may look into adding it later).
This is an item that simply holds a list of Spawners, and when activated, will cause them to spawn in order.
To use this item, create one, along with a Spawner for each level you want your spawn to be, then add the Spawn to the Controller's list.
Here's a video of the LeveledSpawnController in action - The Moonglow Graveyard now spawns increasingly difficult undead until it culminates in a fight with an Ancient Lich:
If you experience any problems with this, don't hesitate to post in the discussion!
I'm always looking to improve my projects.