Psionicsts, normally possessing terrific offensive capabilites, may find themselves helpless against a foe who has some sort of inate, or magical resistance to their mental attacks. Upon encountering such a foe, they are not helpless however, this battle simply becomes a battle of minds. The psionicist's mind attempts to overload and weaken the defenses of the target's mind. A successful psychic purge, can lower the ability of the target to defend himself from mental attacks for a short time, allowing the psionicist to press the attack.