Been Trying to Balance This Out

[FF Fan]

Ipsen's Castle
Spell Card
Field
Monsters with an Original ATK or DEF of 1500 or more lose 1000 ATK or DEF for each 1000 Original ATK or DEF they posses. Monsters with an Original ATK or DEF of 1400 or less gain 2000 ATK or DEF, but lose 300 ATK or DEF x their level. All increases and decreases to ATK and DEF are reversed (except for this card) as long as this card is face-up on the field.

Before someone mentions that this comes from a game. Icy a mod here posts written cards from games here as well.
If you are familiar with this location from FFIX could I get some help on how to balance this while it still basically does the same thing? You know making the weakest monsters the strongest monsters and the strongest monster's the weakest ones. The way I have it now it would be more ideal to use a bunch of 1400 ATK monsters because even though their ATK might decrease by 1200 from being a Level 4 their ATK will end up being 2200 which would still be higher than a Level 1 Original 0 ATK monster.