Semidar is the Champion of the Abyss Spawn. She is about twice the size of a normal Succubus.
Semidar has the same life draining abilities that the normal Succubus and in addition to that she also has a very dangerous melee attack.
She has a very strong dislike for male characters and will reflect any spells they cast on her back onto them and heal herself in the process. A single fireball cast by a male mage can sometimes be suicide even from full health.
Female characters are not affected by this ability and are free to cast as many spells as they please, without getting any damage reflected.
As a male character, the only way to prevent the spell reflection is to polymorph into the shape of a female. That way you won't get any spells reflected.
When Semidar is killed in Felucca, a Scroll of Power will be placed in the backpack of some of the players who damaged her. Additionally one of those who damaged her will also get a "Skull of Pain", which is one of the six skulls needed to summon the Harrower.