Goat format ruling
Mage Power
Card effect (current official text)The equipped monster gains 500 ATK and DEF for each Spell/Trap Card you control.
Rulings
- Mage Power includes itself, Field Spell Cards on your side of the field, and monsters acting like Equip Spell Cards, such as Union Monsters.
- It does not matter if the Spell and/or Trap card(s) on your side of the field are face-up or face-down.
- The only Spell/Trap cards included in the effect of Mage Power are the ones controlled by the person that is in control of the Mage Power. If your opponent takes control of your monster that is equipped with your Mage Power, Mage Power would still only count the Spell/Trap Cards on your side of the field. So if I have a Gemini Elf equipped with Mage Power and 2 Set Spell/Trap Cards and my opponent takes control of the equipped Gemini Elf, they would not count how many Spell/Trap cards are on their side of the field. Only the ones on my side of the field would be included in the effect of Mage Power.
- Q: When the control of a monster changes while equipped with "Mage Power" or "United We Stand," what side of the field is used for calculating the effect increases? A: The person who played the spell card.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Goat forum — sourced change requests get reviewed.