|Orion can be advanced and its rez cost is lowered by 3 for each advancement token on it.|
Trash 1 program.
Resolve a subroutine on another piece of rezzed ice.
End the run.
|And seeking prey he then took aim.|
As with the other "space ice" from Order and Chaos, Asteroid Belt, Wormhole and Nebula, placing advancement tokens on this lowers its rez cost. Those tokens stay on the card even after it's rezzed, keeping its rez cost down after you've spent it. On the one hand, this makes Emergency Shutdown less effective, as it'll remain cheaper (or even free) for you to rez it a second time. On the other hand, it also makes Blue Sun less effective, as you won't get as much (or any) credits for swallowing it back into HQ either. The only way around these is to move the advancement tokens after rezzing the ice, such as with Constellation Protocol or Trick of Light (or to ignore the ability to advance it entirely, and simply rez it for free with, say, Priority Requisition or Eliza's Toybox).