The goal of these two spell pieces is to provide some more control over the frequency of spell availability.

Trick: Cooldown would make a spell unusable for a certain period of time. Attempts to cast it wold fail with no (or minimal) psi usage. This would allow a wider variety of spells to be usable with the Exosuit in particular. Adding a cooldown to a chestpiece that causes knockback would allow you to create a far more powerful knockback, at the cost of having the spell only available every few seconds or a more expensive leg spell that only performed it's function every 10 seconds.

My primary use case for Selector: Psi Energy would probably be to run it through an inverse then multiply to provide a threshold for placing a spell on cooldown. I'd love to use it to scale spells, but that would require spells to variable casting costs.