Should the hide from undead be a supernatural ability that allows it to remain invisible to undead even when attacking (similar to greater invisibility)? Or just make it an at-will SLA?
Organization: Solitary or x (2-12)
x = Guard detail?
Challenge Rating: 9? They are better than crypt wardens (CR 8), but a few HD less than unying coucilors (CR 9), although their spells and martial abilities might offset the difference
Treasure: Double standard?
Advancement: x (We could go "by character class", allowing cleric levels to stack with their innate spellcasting, or provide an "advanced varthas" sidebar to explain how to improve spellcasting with increased Hit Dice).
A vartha stands 5 to 7 feet tall and weighs x pounds.