Descripción:

Once per turn: You can target 1 DARK Machine monster you control and 1 face-up card your opponent controls; destroy them. If a monster you control whose original Attribute and Type are DARK and Machine destroys a monster(s) your opponent controls by battle or by its own effect and sends it to the GY: You can inflict damage to your opponent equal to half the original ATK of 1 of those destroyed monsters in the GY. You can only use this effect of "BM-4 Blast Spider" once per turn.