Edison format ruling
Curse of Aging

Card effect (current official text)Discard 1 card from your hand. Decrease the ATK and DEF of all monsters on your opponent's side of the field by 500 points until the end of the turn this card is activated.
Rulings
- You cannot decrease ATK/DEF by 1000 points by discarding 2 cards; you can only discard 1 card.
- Discarding a card is a cost.
- The effect of Curse of Aging is not applied to face-down monsters. It is only applied to the face-up monsters on the field when Curse of Aging resolves. It is not applied to monsters Summoned after Curse of Aging resolves, either. (Similar to Limiter Removal). This means that even if face-down monsters are flipped face-up in the same turn, their ATK or DEF are not changed by the effect of Curse of Aging, even if they were on the field (face-down) when Curse of Aging resolved.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.