Edison format ruling
Temple of the Sun

Card effect (current official text)Face-up monsters you control that were Special Summoned from the Graveyard gain 300 ATK.
Rulings
- If your opponent Special Summons a monster from the GY and you take control of it, it will gain the bonus from "Temple of the Sun" while you control it.
- Monsters Special Summoned before and after the activation of "Temple of the Sun" will still gain the bonus from "Temple of the Sun."
- If there are multiple copies of "Temple of the Sun" their effects are cumulative. (+600 ATK for 2, +900 ATK for 3)
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.