Effect that lights up one light at a time

This sounds like an Absolute Effect.

Action 1, put 100 in the Level column
Action 2, put 0 in the Level column

This will fade affected channels to 100 and then to 0.

On the right hand side there is a field for Trail, use Solo.

This effect can be applied for any selection you want, it will follow the order of the channel selection. You can use {Offset} {Random Channels} on this selection.

Chan 1 [+] 3 [Thru] 6 {Offset} {Random Channels} [Effect] 1 [Enter]

There is a video about this:
Eos Video Learning Series: Level 2, Chapter 14

Awesome, thanks! However, using the random offset kind of works, but it still eventually follows the same order, that order is now just randomised. Is there no real random function in Eos? Or is this possible some other way? Thanks you!

Oh, and also, just tried applying it to 2 different channel selections, and they behave as one, so still only one light is on at a time. Is there a way to have it only be one light at a time within a specific group? I could just copy the effect and use different instances, but I don't think that's ideal.

In the effects editor click on attributes and select random groups and see if that does what you want it to.

In the effects editor click on attributes and select random groups and see if that does what you want it to.

That just cause multiple lights to light up at once, which isn't what I'm looking for unfortunately

So you want it to choose one random channel at a time to apply the effect to and only to that effect? So if you have a row of strip lights, it turns on one random light at any given moment but not multiple?

I don't see an obvious way to do that natively with Eos. You can do it pretty easily with Alva Sequencer though if you bake as animation. Alva 3D will eventually have an effects engine but doesn't yet.