Wherein your humble scribe presents a new monster for Swords & Wizardry (Core Rules), the Cairn Witch.

A Cairn Witch is a fearsome, evil hag-like being that haunts the areas around burial mounds and sites of ancient battles. These creatures possess powerful spell-casting abilities, which they use to great effect. Treat cairn witches as 7th level magic-users. A cairn witch will normally do its best to use its arcane powers to sow discord among an adventuring party, endeavoring to drive the group apart so that its individual members are easier targets for her wrath. Though they are not undead, cairn witches may be turned as though they were 12 hit die creatures.

Cairn Witch: HD 7; AC 4 [15]; Atk 1 weapon or 2 claws (1d4 or 1d3/1d3); Move 9; Save 9; CL/XP 11/1700; Special: spells, 40% magic resistance, half damage from non-magic weapons.