OCG Rulings

• You cannot use Fusion Substitute Monsters like "Goddess with the Third Eye" when Fusion Summoning "Elemental Hero Absolute Zero". However, "Beastking of the Swamps" and "King of the Swamp" are WATER-Attribute Monsters, so they can be used as normal.^[1]

Previously Official Rulings

These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami.[2] They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: [3][4][5][6][7][8][9][10]

References

1. ↑ Konami FAQ: When Fusion Summoning "Elemental Hero Absolute Zero", can Fusion Substitute Monsters like "Goddess with the Third Eye" be used?
2. ↑ Konami Judge Program Forum: Individual Email Rulings VS Individual Card Rulings
3. ↑ UDE FAQ: Individual Card Rulings [A-C]
4. ↑ UDE FAQ: Individual Card Rulings [D-E]
5. ↑ UDE FAQ: Individual Card Rulings [F-H]
6. ↑ UDE FAQ: Individual Card Rulings [I-K]
7. ↑ UDE FAQ: Individual Card Rulings [L-O]
8. ↑ UDE FAQ: Individual Card Rulings [P-R]
9. ↑ UDE FAQ: Individual Card Rulings [S-T]
10. ↑ UDE FAQ: Individual Card Rulings [U-Z]