This spawns without repop timer every time a bard at the appropriate step zones in. It remains up for approximately 10 minutes before despawning. Be sure you are ready to engage when you spawn it.
Strat is basically kite the adds behind the ramp staying within the two sets of dragon skulls. A bard can do this without any trouble as the adds are very slow. Sometimes they despawn when you kill their lich, sometimes they do not. No pattern to how or why. It's Everquest folks. Keeping these adds off your raid wins you the fight.
Liches basically just die when you fight them. No trick to them.
The dragon at the end does a nasty dot ae. RGC or RC clear it up.