Knights: Should have decent skills (at least 55/55) with good equipment and at least level 25 to successfully hunt these. They can do alot of damage so be sure to have Health Potions with you.
Paladins: Run while attacking them with any distance attack. Beware not to come too close to these since they can do a high damage in close combat. Experienced paladins are advised to kill them using Divine Missiles or Divine Caldera in the case they come in group. Since they are usually found with Mummies, Bonelords and other Undead, it is recommended to take priority on the Crypt Shamblers since they are strong when in close combat. A good place to hunt these is in Yalahar, Cemetery Quarter.
Mages: Should keep distance from them while attacking with their wand/rod and shooting fire, energy or Ice Damagerunes or spells. Don't let them come too close because their attacks can kill a mage easily. Can start hunting these as low as level 15, but are commonly found with mummies (or other undead) so take care when doing so.