Water.
Zombie/Xyz/Pendulum/Effect. Pendulum Effect: You can target 1 Xyz Monster you control; attach this card to it as material. You can only use this effect of "Daidaratant the Ooze Giant" once per turn.Monster Effect: 2 Level 4 monstersIf you can Pendulum Summon Level 4, you can Pendulum Summon this face-up card in your Extra Deck. You can detach 1 material from this card; place this card in your Pendulum Zone, then you can add 1 Pendulum Monster from your GY to your Extra Deck face-up. If this card in the Monster Zone is destroyed by battle or card effect: You can place this card in your Pendulum Zone. You can only use each effect of "Daidaratant the Ooze Giant" once per turn.