In the battle against the foul Undead, the healer has an immensely powerful Weapon. Undead creatures are the reverse of living beings, and so are affected by healing spells in a reversed manner. Any Healing effect cast upon an Undead will instead do damage to them. Any Chaos effect, however, will heal the Undead. Similarly, many Earth effects will weaken or debilitate the Undead while Necromancy will do the opposite.
Undead generally have a significant amount of Natural Armor, representing the raw power of the Necromantic energies that animate them. Healing cuts right through an Undead’s armor, avoiding the bulk of its durability and striking straight at the core of its essence. Thus a Cure Wounds spell at 2nd level cast with the incant of “I call upon Earth to grant 10 Healing!” will do 10 points of damage against an Undead creature and ignore its significant Natural Armor completely, while a Cause Wounds spell of the same amount will heal the Undead for 10 points.
Similarly, Celestial Magic has a distinct advantage when fighting creatures not native to Realms of REFUGE as well as magically animated constructs or constructs. Their “Banish” and “Subjugate” spells come in especially useful against these foes. Similarly, when battling the common Elementals of Flame, Ice, Lightning, and Stone, their spells can be especially impactful when blasting away with the opposing Element.