Necron Destroyers have always been a part of my Necron foot list- the fast moving element that swings around to intercept what my opponent uses to zoom up the side of the table or rush into my blocks of Warriors vs. allowing me to shoot at them a few turns as I march forward.
For the most part they have remained consistent with each edition of 40K- as Space Marine or heavy infantry killers, with a small exception in 7th. Now back in 8th I feel like they are back in the role of that due to the re-rolls and the strong AP.
I also tend to play in a strong Space Marine meta so they work extra well, if the guys I primarily played against had IG or Eldar as their armies, less so.
I’ll roll them with a Destroyer Lord for more lolz and often deploy in the center back of the table- from here I can stay center and back up my advancing Warriors, OR swing right/left and work up the side of the table.
Wish there were more super tactics with them, but all in all a solidly performing unit, and that is the tactics of it as is.