Any tricks to removing a stuck/stubborn/rusted-in place bleeder?

Brake bleeder? Heat is worth a try but keep in mind any moisture inside the line will boil causing pressure or steam. In my experience the bleeders snap yes you can drill and tap but its tricky surgery because you don't want to drill into the seat. Id use PB blaster and an impact source like an impact screw driver with a dead blow hammer. If that didn't work Id then apply a little heat and more dead blow impact etc. You could use an air impact wrench but id go 3/8 drive and start on a low air setting and slowly ramp it up. Like said the bleeders usually break off in extreme cases...