The official GemStone IV encyclopedia.
Seemingly cobbled together from leftover bodily parts, no two shrickhen are alike. One may have the lower body of a troll supporting the torso of a fire salamander from which a dark orc's arm extends on one side and a gremlin's arm extends on the other, all topped by a timberwolf's head. A second may have a mezic's leg, a coyote's leg, a pyrothag's arm, and a shan warrior's arm, each connected in almost the right place to the torso of a krolvin warfarer, with the entire grouping utilizing the one-eyed head of a cyclops for navigation. These hideous conglomerations definitely have two things in common: a total lack of fear and an insatiable need to consume flesh.
The Shrickhen are easily the most dangerous of the enemies in the Labyrinth, almost certainly because they regularly use and cast Elemental Wave (410) and Major Elemental Wave (435). Furthermore, they tend to spawn with these spells active, so upon initially entering the Labyrinth, or after killing several Shrickhen in a short period of time, caution should be exercised when engaging the newly spawned Shrickhen. Because of this, it is of the utmost importance to prevent casting by a Shricken; unlike the Dhu Goleras, who with more than a dozen spells, may cast something less dangerous, the Shricken has a very high chance of casting these two spells.
Another trick the Shricken has up its sleeve is the very rare chance that it will spontaneously rip its own arm off and throw it at you, with a fairly high ranged AS. While a Shricken can usually only do this once, the above average AS can take you offguard and hit many characters, even in defensive stance. This might be enough damage to stun you long enough for the Shrickhen to prepare and cast one of the Elemental Wave spells. Aside from this, however, the Shrickhen are not very "characteristic" undead creatures, and stun just as well as most living targets.
Shrickhen have a tendency to run around spelling both themselves and Dhu Golerases up with casts of Elemental Defense II (406) and Elemental Defense III (414). They will do this even with no players in the room, and it is not an uncommon situation. Despite the risk of engaging newly spawned Shrickhens, one can also take advantage of their lack of some defensive spells if you can catch them early. They do not seem willing to cast these spells on Moulis, but on rare occasions, a Moulis may cast Strength (509) on a Shrickhen..
Their use of the elemental waves has one advantage, which is that they will frequently knock down Moulis and Dhu goleras in the same room as you. This will help level the playing field somewhat should you be stunned or stuck in roundtime.