Heartseeker

''You transform the pointed weapon into a true harbinger of death, a weapon which sprouts roots when it hits its target. The roots and branches seek out vital organs, instantly killing or lethally wounding the victim.''

This terrible spell is cast on a piercing weapon made partially of wood, usually a spear or an arrow. When the weapon damages a creature, the wooden shaft of the weapon begins to sprout as if growing. The roots and branches seek out vital organs as a source of nutrients. If the creature fails a Fortitude save, the vines burst through the victim's vital organs, killing him instantly. If the save is successful, the creature manages to pull the weapon out but takes 10d8 points of damage. The weapon is destroyed after being used. Creatures immune to critical hits automatically make their Fortitude save.