Blade ward 2024 question?

Blade ward in 2024 now subtrack from attack roll instead of grant resistance for physical damage

now i have a question, it effect only one attack and the spell is dispel(like Guidance that effect only one roll) or effect all attack until the spell end?

Whenever a creature makes an attack roll against you before the spell ends, the attacker subtracts 1d4 from the attack roll

And this is just a cantrip?? This is OP for a cantrip. It's like a save throw-free Bane if all you need is to protect 1 person. Holy moly.

I see. Range of Self. I guess that is pretty serious limiting factor. Dang, Moon Druids should totally be casting this. Oh wait...