When this card is sent to the Graveyard: You can target 1 face-up monster on the field; equip that target with this card. That monster loses 500 ATK while equipped with this card.
Rulings
Individual Card FAQs
Missing the Timing: “Archfiend of Gilfer” is a “when… you can” optional Trigger Effect. This means that “Archfiend of Gilfer” being sent to the Graveyard has to be the very last thing that happened in order to activate its effect.
This card's effect will activate when it is sent to the Graveyard from the field, hand, or Deck. This card's effect will activate when it is sent to the Graveyard while it is a Monster Card or an Equip Card.
If multiple "Archfiend of Gilfer" cards are sent to the Graveyard at the same time, all their effects will activate and form a chain.
DARK|
Level 6|[ Fiend / Effect ]
ATK 2200|
DEF 2500