Q: How does Respawn work?
A: Each map will have set respawn points (usually four). Using Respawn, a dead or dying character will be restored to full hit points and healing surges, all encounter powers and power points restored, all failed death saves removed, all conditions removed (besides end of encounter conditions), and then teleported to a respawn point (either random or determined as per the map).
The dungeoneer will then will be able to take their full turn.
Animal Companions are unaffected by Respawn.