Can i declare an attack zone, see if my opponent plays any tactics, and then not declare any attacking units? For instance, my opponent plays Sigmars intervention during the window after i declare, and redirects the attack to a brick wall of counterstrike. Well, i obviously would be sending my units to their doom if i declared them as attackers, right? The rule book says i can declare which of my units are attacking if any. So... wtf? If thats the way it is, every turn i can just lie and say im attacking a zone, see if he wastes something, and then not do anything.

cant see why not but seriously why would anyone play Sigmars Intervention in that window and not after Attackers have been declared?

Badger is right, the defender would be stupid to show his hand that way. The way I taught my son to play, ALWAYS wait till the last window of opporunity to play a tactic/action.