Vouiburial, the Dragon Undertaker

If this card battles a monster, neither can be destroyed by that battle. During the Main Phase, if a monster(s) your opponent controls is sent to the GY: You can activate the following effect, based on where this card is at activation (but you can only use each effect of “Vouiburial, the Dragon Undertaker” once per turn);
● Hand: Special Summon this card.
● Field: Make 1 Effect Monster your opponent controls lose 1500 ATK, then if its ATK becomes 0 by this effect, you can destroy it.