Basically this, the difference is that it's an encounter effect and not a subroutine.
I'm fine with this discussion being moved there, I posted it in Netrunner General because it's more about the design space rather than the specific examples and there's no subforum for variants.
This would be a different effect; I was intending for it to be a one-shot ice, just like a one-shot icebreaker.
There are cards that interact with power counters (eg, Helium Deposit) and I think the templating doesn't need to be that long.
I don't want the effect upon rez though, that would lead to weird interactions with cards that allow the corp to rez ice, especially outside of a run. I think an "on-encounter" effect is probably the best way to go. Think of it as a single use Troll.
I think you're right that Fuse might be too powerful with Blue Sun, but on the other hand it gives runners something to effectively parasite in that matchup These examples are just meant to show what I was talking about, not really as proposed cards.