Tengu format ruling
Armed Changer

Card effect (current official text)Send 1 Equip Spell Card from your hand to the Graveyard to activate this card. If the equipped monster destroys a monster by battle, the controller of this Equip Card can add 1 monster with ATK equal to or less than the equipped monster from their Graveyard to their hand.
Rulings
Send 1 Equip Spell Card from your hand to the GY to activate this card. (1) If the equipped monster destroys a monster by battle, the controller of this Equip Card can add 1 monster with ATK equal to or less than the equipped monster from their GY to their hand.
- Sending 1 Equip Spell Card from your hand to the GY is a cost. You can't activate this card while Macro Cosmos is active, since you can't pay the cost.
- The (1) Trigger-like Effect is optional, it activates & resolves on the field.
- This effect activates in Substep 7 - End of the Damage Step.
- If the monster equipped with this card destroys a monster like "Sangan" or "Mystic Tomato", its effect will form a chain with them according to the rules of simultaneous effects.
- If the monster equipped with this card destroys a monster with equal ATK, then its effect will not activate, since "Armed Changer" is sent to the GY at the same time as the opponent’s monster.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.