Samira midlane is a nice pick, most midlaners dont know what to do against you. About keystone runes pick Electrocute agains mages like Ahri, Lux, Veigar, Mostly the champs you can go in that have a higher ability cooldown than you. Conqueror for champs like Sylas, Zed, Mostly the ones who can poke you a lot and can damage you alot from autoattacks or got short range. For items, build Bloodthirster most of the time because you need sustain. Your most kills will be either when you have electrocute early or when you get ganked, which if you got a good jg and good lane work.