To cast predator's kiss on a creature, the caster must pierce or scratch that creature with the material component sufficiently deeply to draw blood; if the target is unwilling, a successful melee attack must be made with the wand, which is considered a +2 magical weapon for this purpose, doing 1-2 points of normal damage in addition to the effect described below.  The creature also immediately loses a number of hit points equal to the creature's level; this is halved for a willing target.  This damage cannot be healed by any means until the spell is over.  Two effects are set in motion upon a successful hit.  First, the caster will be able to supernaturally "smell" the blood which is drawn whenever they are within a mile of the target creature; this allows them to know the creature's exact location, and their general state of body (healthy, poisoned, fatigued, diseased, and/or wounded; in the last two cases they can also tell in general terms how severe the damage or illness is) and mind (emotional state, and whether they are asleep, unconscious, charmed, or insane).  This also grants the caster advantage on attack rolls against any being within 5' of the target, as long as the target is able to see that being.  Secondly, the target gains the ability to heal their own or another creature's wounds by licking them, restoring (1d4 x the amount of hitpoints lost when this spell was cast) hit points of damage; this ability cannot heal damage from any casting of this spell, or from acid.

If cast in a spell slot 1 level higher, a willing target of the spell gains a limited ability to sense its caster as the caster senses them. Once an hour, the target can concentrate to learn the caster's exact location OR whether they are wounded or diseased, and in general how severely OR if they are asleep, unconscious, charmed or insane. If cast in a spell slot 2 levels higher, the target can learn two of these things; and if cast in a spell slot 3 levels higher, they can learn all three.