What a TH8 layout has to stop
Dragons, Hog Riders and Lightning spell attacks are some of the most common strategies at Town Hall 8. A good TH8 layout keeps air defenses away from the edges, so they cannot be zapped and reached easily, and places Giant Bombs where Hog Riders are likely to path between defenses.
Dark Elixir becomes valuable at this level, so farming and hybrid layouts usually protect the Dark Elixir storage inside the core.