When this card destroys a monster and sends it to the Graveyard as a result of battle, inflict damage to your opponent's Life Points equal to the Level of the destroyed monster x 500 points.
Rulings
Individual Card FAQs
The Level of the destroyed monster is the original Level.
You can use "Barrel Behind the Door" against "Needle Burrower"'s effect.
DARK|
Level 5|[ Machine / Effect ]
ATK 1700|
DEF 1700