Tengu format ruling
Armored Cybern

Card effect (current official text)Once per turn, you can either: Target 1 "Cyber Dragon" you control, or 1 Fusion Monster you control that lists "Cyber Dragon" as Fusion Material; equip this card to that target, OR: Unequip this card and Special Summon it. Once per turn, while equipped to a monster by this effect: You can target 1 face-up monster on the field; the equipped monster loses exactly 1000 ATK (even if this card leaves the field), and if it does, destroy that target. If the equipped monster would be destroyed by battle or card effect, destroy this card instead.
Rulings
(1) Once per turn, during your Main Phase, you can equip this card to a Cyber Dragon you control, or to a Fusion Monster you control that lists Cyber Dragon as a Fusion Material Monster, OR unequip it to Special Summon this card in face-up Attack Position. (2) Once per turn, while equipped to a monster by this effect, you can decrease the equipped monster's ATK by 1000 and destroy 1 face-up monster. (C) (A monster can only by equipped with 1 Union Monster at a time. If the equipped monster would be destroyed, destroy this card instead.)
- Armored Cybern's effect to destroy 1 monster targets. The ATK of the equipped monster is decreased when this effect resolves.
- If Reverse Trap is activated, the equipped monster will gain 1000 ATK instead of losing 1000 ATK. When the turn ends, the ATK gain will become an ATK loss.
- When Armored Cybern is unequipped or removed from the field, the ATK lost with its effect is no longer applied.
- When Armored Cybern is equipped to a monster that is unaffected by the effects of Spell Cards, you can activate its effect but the effect disappears because the equipped monster's ATK cannot be reduced with Armored Cybern's effect.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.