Tengu format ruling
Imperial Custom

Card effect (current official text)Face-up Continuous Traps cannot be destroyed by battle or card effect, except "Imperial Custom". You can only control 1 "Imperial Custom".
Rulings
(1) Face-up Continuous Trap Cards cannot be destroyed, except Imperial Custom. You can only control 1 Imperial Custom.
- The (1) Continuous-like Effect does not activate.
- This effect only protects Continuous Traps from destruction.
- Continuous Traps which destroy themselves (ex: Call of the Haunted) are not destroyed.
- Continuous Traps still destroy themselves if maintenance costs are not paid (ex: Mirror Wall).
- Trap Monsters (ex: Zoma the Spirit) can't be destroyed by battle or card effect.
- If Heavy Storm would destroy face-up Continous Trap Cards, Imperial Custom is destroyed but all other face-up Continuous Trap Cards (including your opponent's) remain.
- Continuous Trap Cards can still:
- be flipped face-down (a Trap Monster targeted by Book of Moon).
- be removed from play (by Caius the Shadow Monarch).
- have their effects negated (by Jinzo).
- have their activation (playing face-up) negated (by Dark Bribe). If the activation of a Continuous Trap Card is negated, it is sent to the GY. It was never face-up on the field.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.