By casting this spell on a small gemstone, the caster prepares a magical snare that forces creatures shifted over into an alternate state of being to change phase. The gem can be placed, thrown or moved around as desired with the effect area centered on wherever the gem is located. Creatures existing out of phase with the caster, whether through an ability, spell or magic item, entering the warded area must save or be forced to immediately change state. Such creatures assume the caster's state of phase and are held in that state for the duration of the spell, even if later leaving the warded area. Such creatures may then become visible and vulnerable to standard attacks. This spell is effective against creatures in the astral or ethereal plane, creatures using blink, dimension door, etherealness, phase door, rope trick and similar spells that cause a change of plane or state, the effects of which are suspended for the duration of the spell, rather than dispelled. Phase snare is also effective against such monster powers as a xorn's earth glide ability and a phase spider's ethereal jaunt ability. As a general rule the spell only has effect on supernatural abilities. The material component becomes cracked, charred and burned out if ever successfully used to ensnare an out of phase creature, but is otherwise reusable.