Normally, limited time events are just about the top of my priority list, but DDO's Mabar Festival somehow failed to make the cut.
The Mabar event appears to be as much of a tech demo for instanced public group content as an actual event. Delara's Graveyard, which is ordinarily a public lobby devoid of anything hostile, is suddenly overrun by the undead. Non-aggro mobs of approximately your level spawn near you when you enter the zone during the event. They drop tokens which can be exchanged for loot. When enough tokens are handed over to the NPC's, players can participate in a public raid encounter for more tokens used to upgrade the loot.
On paper, it's nice enough, but the execution is a bit rough around the edges. As a low level player, it's easy to get yourself killed because either you accidentally hit something much tougher than you (low level skeletons and high level mummies don't look all that different in the dark) or because you wandered too close to something that someone else was fighting and got one-shotted by its AOE. Higher level characters earn "mote" currency more rapidly, and prices are set accordingly.
My guess is that this event is more fun as a max level character in a group. Given that I had neither, I gave the event a brief try and called it a night. For unknown reasons - perhaps related to server stability questions, as DDO has not previously had anything that puts this many players in a single combat zone - the event was very short, and ended before I got back to it. Oh well, maybe next year.