(Spell Compendium variant, p. 284)
Must be neutral evil
Granted power (Su)
You gain the ability to smite good with a single melee attack once per day. You add your Charisma bonus (if any) to your attack roll and deal an extra 1 point of damage per class level. This smite attack is treated as evil-aligned for the purpose of overcoming damage reduction. At 5th level and every five levels thereafter, you can use this smite attack one additional time per day.
Note on Planar Domains
A planar domain counts as both of a cleric's domain choices. The granted powers of a planar domain are more potent than those of other domains, and each level offers two spells from which a cleric can choose when preparing spells. Each day, a cleric with access to a planar domain chooses one of the two spells available to prepare in his domain spell slot for each spell level. Unlike other domains, planar domains each have an alignment requirement that must be met by a cleric who wants to access the domain.
A cleric need not select a specific deity to have access to a planar domain. A cleric who devotes himself to a specific alignment (LG, NG, CG, LN, CN, LE, NE, or CE) rather than a deity can select a planar domain in place of his two normal domain choices. If the DM wishes, he can make domains specific to other planes, using these as representative guides.