[PU4, Powers] What does Cosmic power modifier actually do?

[Gurps Fan]

Originally Posted by David Johnston2

But the Silver Surfer really does have "The Power Cosmic" as his power source. So do the New Gods from the competition's stuff.

That sounds like mixing game effects up with in-game explanations. "My power source is cosmic bla bla bla..." is an in-game explanation, not effect, and not what we pay character points for. For instance, "Spirit power modifier, -25%" is worth -25% because of its fickleness and required disadvantage, not because of the fact that "my power source is spirit" itself.

Originally Posted by sir_pudding

You can't have Cosmic Powers without a tier system. Allowing them at all makes it a two tiered system at least. If you don't want that, don't allow Cosmic Powers.

Ah, I see your point. Then assume a (default) two-tier system. Game-mechanically, the effect of "being in the highest tier in two-tier system" is being immune to any non-Cosmic coutermeasure. This is too useful to be priced at "free".