Sunken Seabed Ruins (X-BT03/0044EN) (X-BT03)

During your main phase, when a size 3 or greater monster enters your field, if this card is in your drop zone, you may pay 1 life. If you do, cast this card from the drop zone.
[Set] (This card remains on the field.)
3 or greater damage dealt to you by monster effects are reduced to 0.
When monsters on your field attack, put the top card of your deck into your gauge. This ability only activates once per turn.