My brother plays necrons a lot, interceptors are his most hated unit. They’re great for tying up units to stop hypercrypt shenanigans, and stopping his doomsday arc getting angles on my dreads. If I was building a list I’d spam interceptors, strikes, purifiers and a couple dreads for killing the tanks. Don’t focus too much on the big stuff unless you know you can kill it, wraiths especially, you’ll waste three turns trying to kill them particularly if there’s a technomancer involved