TOPIC: ring of Evasion

i cant seem to find this on the token list so could someone tell me what it dose

Ring of Evasion: Wearing this ring allows the user, (once per encounter/room), to take NO DAMAGE from a spell effect or trap that allows a normal Reflex save for one-half damage.  So, if the wearer makes her save, the wearer takes no damage instead of one-half damage.  The effect of this ring works on only the first Reflex save for damage the player makes in an encounter (room).  If the player fails a save while wearing the ring, the player takes full damage as if not wearing the ring at all.<br /><br />See page 37 of the token guide.