Goat format ruling
Big Bang Shot

Card effect (current official text)The equipped monster gains 400 ATK. If the equipped monster attacks a Defense Position monster, inflict piercing battle damage to your opponent. When this card leaves the field, banish the equipped monster.
Rulings
- When the monster equipped with Big Bang Shot is destroyed, and Big Bang Shot is destroyed as a result of this, the equipped monster is not removed from play.
- If a monster equipped with Big Bang Shot is Set, it is no longer a target of Big Bang Shot so Big Bang Shot is sent to the GY and the monster is not removed from play.
- When you send Big Bang Shot to the GY with Emergency Provisions, the monster is removed from play at the same time.
- When equipped to Guardian Ceal, if you send Big Bang Shot to the GY as a cost for Guardian Ceal's effect, Guardian Ceal is removed from play but Guardian Ceal's effect still resolves.
- If a monster is equipped with Big Bang Shot and Fiber Jar is activated, both Big Bang Shot and the equipped monster are shuffled into the Deck, and the equipped monster is not removed from play even though Big Bang Shot was removed from the field.
- If you equip your Big Bang Shot to your opponent's Dark Magician, and Dark Magician attacks your Giant Soldier of Stone, the opponent of the owner of the Big Bang Shot takes the damage (so your opponent, who attacked with Dark Magician, takes 900 points of damage.)
- The battle damage caused when the equipped monster attacks a Defense Position monster is considered to come from the equipped monster, not from Big Bang Shot. So a Don Zaloog equipped with Big Bang Shot could still make the opponent discard 1 card when attacking a face-down monster with low DEF.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Goat forum — sourced change requests get reviewed.