Publication:Dread Codex/New Spells/Frost Symbol

Undead creatures animated by you are imbued with a icy sigil that floats just above their heads. The body of the creature radiates cold, and its eye sockets glow with blue energy. The spell affects a number of hit dice of animated undead equal to your level.

Undead with the frost symbol gain the cold subtype as an extraordinary ability, granting them cold immunity and exposing them to double damage from fire except on a successful save. Additionally, undead affected by the frost symbol inflict an extra 1d6 points of cold damage when they strike with a natural weapon. Creatures touching or striking the symbol-bearing undead with a natural weapon also suffer this damage. This spell does not stack with other symbol spells.