From TMW: rEvolt
The ultimate "monster" in The Mana World. Luvia is the strongest mob in game and the final boss in the Quest about The Illia Sisters. It's impossible to fight her alone, not only because she herself is very strong, also because she is always supported by Witch Guards and Demonic Spirits.
There are always 7 Demonic Spirits around her. No matter how much of them you kill there will always spawn another one right after. Additionally every 20 seconds another Demonic Spirit and every 60 seconds a Witch Guard appear. Therefore it needs great teamwork to fight Luvia and her summons.
Luvia herself hits very hard, and due to Luck of 255, it is impossible to prevent getting a critical hit from her. Also Range 5 means she can hit you even when she is far away. Mages are nearly useless fighting Luvia directly as her Magical Defense is at an overwhelming 92%, but mages are very important luring away her summons with the #itenplz spell and healing the other team members with #inma. Warriors are the best choice to fight Luvia directly as they don't get killed that fast.
Apart from The Illia Sisters quest Luvia is often spawned in Game Masters events. Besides that they are fun, another reason to join these events are that Luvia gives you a lot EXP after defeating her.