Tengu format ruling
Great Shogun Shien

Card effect (current official text)If you control 2 or more face-up "Six Samurai" monsters, you can Special Summon this card (from your hand). Your opponent can only activate 1 Spell/Trap Card each turn. If this card would be destroyed, you can destroy a face-up "Six Samurai" monster you control instead.
Rulings
(U) If you control 2 or more Six Samurai monsters, you can Special Summon this card from your hand. (1) Your opponent can activate only 1 Spell/Trap Card each turn. (2) If this card would be destroyed, you can destroy a Six Samurai monster you control instead.
- The (U) Unclassified Effect works like a built-in Special Summon. This Summon does not start a chain.
- The (1) Continuous Effect applies so long as Great Shogun Shien is face-up on the field.
- Your opponent can activate either 1 Spell Card or 1 Trap Card each turn; not one of each.
- If the activation of your opponent’s Spell/Trap Card is negated (by "Dark Bribe), they can still activate 1 more Spell/Trap Card after that.
- This effect applies during both players’ turns.
- The effects of face-up Spell / Trap Cards can be activated without restriction.
- The effects of Spell / Trap Cards in the GYs can be activated without restriction.
- If your opponent activates a Spell / Trap Card, and later you Special Summon "Great Shogun Shien" (or flip him face-up), your opponent can activate 1 more Spell / Trap Card this turn.
- The (2) Continuous Effect does not activate.
- This effect does not target. You cannot destroy a face-down "Six Samurai" monster instead.
- This effect applies while resolving the effect (ex: Call of the Haunted, Raigeki Break).
- Your other "Six Samurai" monster is considered to be destroyed by this (your) effect.
- Example: If "Ring of Destruction" targets a "Six Samurai" monster, and you destroy a different "Six Samurai" monster instead, zero damage will be inflicted by "Ring of Destruction".
- This effect can apply in Substep 4 - Damage Calculation. The substitute "Six Samurai" is sent to the GY in Substep 7 - End of the Damage Step, it is not treated as 'destroyed by battle'.
- You cannot destroy 1 "Six Samurai" to save multiple other "Six Samurai" monsters at the same time.
- Example: If Mirror Force would destroy 2 of your Six Samurai monsters, you must destroy 2 Defense Position Six Samurai monsters to save those two.
- This effect cannot apply if the substitute "Six Samurai" is also being destroyed by the effect.
- Example: If Mirror Force would destroy all your Six Samurai, you cannot substitute any.
- If you control 2 "Six Samurai" monsters, and 1 of them equipped with "Legendary Ebon Steed" would be destroyed, the effect of "Legendary Ebon Steed" must be used. You cannot choose to destroy another "Six Samurai" monster instead.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.