To probably shake things up. I know I would hand pick a couple of species off their planets.

[He already has, honestly- or more like they come to him, after Aku fucks up their homes away from Earth. But enough about him, the mortal raises an interesting point]

It's not even death by gladiatorial combat. Here's my theory:

[The demon steeples his fingers and furrows his GREAT, FLAMING EYEBROWS in contemplation.]

...They have a boring idea of fun!