Need some answer with the ruling of this card.
Is this card chainable? (enemy activate treacherous then you activate this card)
Can you activate this card at enemy turn?
...How are so many people that dense? Neither effect is chainable. And, being a Normal Spell, that would ALWAYS be the case. (Actually, even the GY effects of Quick-Plays like Destruction Swordsman Fusion are Spell Speed 1 and can't be chained to anything or used outside your Main Phase.)
I believe ppl is that dense bcuz the media has corrupted the mind of plenty of western folks. Have you played resident evil 2 remake? that's what happened here. Heavy pollution.
This card is a spell speed 1, just like Galaxy cyclone it can only be activated on your main phase.
While in the graveyard this card is treated as a normal spell.
"for the rest of this turn" means exactly what it says, for the rest of the turn you used the effect. It doesn't influence WHEN you can use it at all, and I'm not sure why you thought it did.
All GY effect that doesn't have the clause "(Quick effect)" or "during either player turn..." can only be activated during your main phase. Only trap's GY effect (like U.A. Penalty box) can be activated anytime.
Its not chaining towards treacherous , but rather active right after treacherous resolves. Thats also a reason neos didnt get destroyed after being struck by divine wrath, in spite of being a counter trap. He still get his eff negated tho. This is he same case with neos fusion protection eff.
BTw in case of enemy turn, you should notice neos fusion and this card has a huge difference. Neos fusion protection is being actived in RESPONSE to neos destruction, meanwhile this card has to be actived manually beforewards. It is not responding to anything, which mean you cant use it during ur opp turn.