Liberator Eto (Quarter Century Secret Rare)

Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand or GY) by paying half your LP, while your opponent has a Monster Card in their field or GY with an effect that activates in the hand or Monster Zone in response to a card or effect activation. You can only Special Summon "Liberator Eto" once per turn this way. This card's Special Summon cannot be negated. This face-up card cannot be used as material for a Fusion, Synchro, Xyz, or Link Summon, also during your turn only, it is unaffected by monster effects activated on your opponent's field.