These are just my feelings on how Counter Traps work.
Counter Traps either respond or chain to something that happens. Whether that be a summoning declaration or an attack declaration. They respond to or chain to something. Such as
Solemn Judgment chaining to
Dust Tornado that's chained to your
Royal Decree that will negate their
Widespread Ruin,
Call of the Haunted, etc..
Negate Attack has the same activation timing as
Magic Cylinder. It has a similar effect as
Magic Cylinder just with a slight difference in what it does after it negates the attack.
Negate Attack can directly respond to the declared attack.
The actual real question I would like to have answered is if it eats up the Turn Player's priority to respond to his/her own attack with a Spell Speed 2 or higher effect?
Honestly it doesn't really matter that much considering
Negate Attack can still activate directly to the declaration of the attack or in a chain created directly in response to the attack.
Doesn't matter because the timing is still valid. The real question is if Turn Player's priority taken away if
Negate Attack is activated or not.
I believe I've read somewhere that
Solemn Judgment and
Horn of Heaven eat Turn Player's priority when he/she declares a summoning.
So the more important question I think we should resolve is if
Negate Attack eats the Turn Player's priority or not.
Because with the whole
Sangan/Witch v.s.
Solemn Judgment/
Horn of Heaven ruling, it has come to my understanding that Counter Traps eat Turn Player's priority.
Meh, I need some food...lol