Quoted from crwjumper:
Sorry - I should have said "when you start a villain multiball, and another villain multiball is qualified". I have edited my post for clarity.
"Season" multiballs - obtained by COMPLETING a minor villain from each of the three seasons:
- Gas Attack
- Robin Holy
Main villain multiball obtained by completing all of the main villains:
- Villain Escape
Ah okay, that makes sense. It's not easy to pull off but you can stack villain escape with a minor villain wizard mode.
You need to bring in or have running the final minor villain needed for a wizard mode into villain escape, then complete that minor villain during the first phase of villain escape, then shoot the saucer to get the wizard mode select screen. Oh and you need Mr Freeze's power running to stop the phase 1 villain escape timer to make it worth it.
I've only done it once but it REALLY built up my villain escape value to the point where I made 8B+ without even getting the super, assumably the super would have been around 8B as well.