Edison format ruling
Proto-Cyber Dragon

Card effect (current official text)This card's name becomes "Cyber Dragon" while on the field.
Rulings
- If "Skill Drain" is active, this card is no longer treated as "Cyber Dragon". You could not use it for "Attack Reflector Unit", etc.
- You can have 3 "Cyber Dragon" and 3 "Proto-Cyber Dragon" in your Deck and Side Deck combined.
- If you Special Summon this card you can activate "Inferno Reckless Summon" and Special Summon "Cyber Dragon" from your Deck.
- You can use "Machine Duplication" and a "Proto-Cyber Dragon" whose ATK has been reduced to 500 or less to Special Summon up to 2 "Cyber Dragons" from your Deck.
- While this card is face-up on the field, it can be used as "Cyber Dragon" for a Fusion Summon.
- If "Proto-Cyber Dragon" is used in the Fusion Summon of "Cyber Twin Dragon", and "De-Fusion" is used on that "Cyber Twin Dragon", you cannot Special Summon the "Proto-Cyber Dragon" from the GY because its name is not 1 of the listed Fusion-Material Monsters. (It’s no longer treated as "Cyber Dragon" while in the GY.)
- If "Prohibition" is activated choosing "Cyber Dragon", "Proto-Cyber Dragon" will not have its name treated as "Cyber Dragon" and can still attack and change its battle position.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.