If you don't have a Stuck Case Remover set, you can improvise one. Pull the decapping rod up as far as you can to get it out of the way. Then use a drill to drill through the primer pocket and tap the resulting hole for a machine screw. Be sure to use lube on the tap, since brass grabs steel and holds it tight, which is what got the case stuck in the first place.
You can place a large nut, socket, or anything else that will give the case room to move, yet provide a flat surface for the head of the machine screw to pull against as you tighten it. You may have to use a washer for the head of the machine screw to bear against. Just tighten the screw and it will pull the case from the die enough to remove it. It only take about 1/8" of travel to break it loose.
Hope this helps.
Fred