Psi crystals are a new mechanic, replacing the role of artifact creatures. Like gold counters or poison counters, they're a per-player resource not associated with any permanent, and maintained between steps/phases/turns.

They have no automatic use, only other cards that can use them.

This card is a token for counting psi crystals, like a poison counter token.

I realise this mechanic only makes sense within this set (like Snow). That's not ideal, but I think it's worth it if it works.

I will make an effort that if you only have one or two sources/sinks, you should still be able to get some use out of them.

Flavour-wise, psi crystals are the resource that this world was settled for, and provide powerful psychic abilities.

And now they are printed in Kaladesh! The flavour is even similar. The main difference is that kaladesh made sure most cards produce and use energy on the same card, and that it matters that they do so

Whereas I didn't get far with the design. I was still hoping to have cards that produce and cards that consume -- not all the consuming cards would make sense to have a free supply, whereas in kaladesh, there's a question of when you spend the energy even if you get it when the card ETBs.