REDU format ruling
Kishido Spirit

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Monsters on your side of the field cannot be destroyed in a battle if the monsters' ATK are equal.
Rulings
- If your monster in Defense Position is attacked by a monster with equal ATK to your monster's ATK, your Defense Position monster will not be destroyed even if its DEF was lower than the attacking monster's ATK.
- When Spear Dragon attacks a Defense Position monster with equal ATK to Spear Dragon, perform damage calculation normally even though the Defense Position monster is not destroyed.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.