You can activate the " 3+" effect multiple times during the same Chain.You cannot activate the " 3+" effect during the Damage Step.You cannot send a " Crystal Beast" Spell Card. For the " 3+" effect, you have to send a " Crystal Beast" Monster to the Graveyard.The effect is Spell Speed 2, so it cannot be used against Counter Trap Cards. The " 3+" effect of " Ancient City - Rainbow Ruins" is a Spell Speed 2 effect that activates in chain to the Spell/Trap Card.If " Demise, King of Armageddon"/" Heavy Storm"/" Malevolent Catastrophe"/etc would destroy " Ancient City - Rainbow Ruins" and at least 1 " Crystal Beast" card in your opponent's Spell/Trap Zone, then " Ancient City - Rainbow Ruins" is not destroyed because of the " Crystal Beast" card.For example, if you have 4 " Crystal Beast" cards in your Spell/Trap Zone, then the " 1+", " 2+", " 3+", and " 4+" effect are applied. " Ancient City - Rainbow Ruins" accumulates the effects.The " 1+" effect of " Ancient City - Rainbow Ruins" will not prevent it from being destroyed when a new Field Spell Card is activated. When an old Field Spell Card is destroyed when a new one is activated, the old one is not considered to be destroyed by an effect.(It is not " once per turn, you can activate one effect".) The " 2+", " 4+", and " 5+" effects can each be activated once per turn.The opponent cannot activate activate its effects. The effects of " Ancient City - Rainbow Ruins" can only be activated by its controller.