Hextech Gunblade is far from a decent early game item, you should not get both Will of the Ancients and Hextech Gunblade as your core items. You could, maybe, keep Hextech Revolver, then build some of your other items, and finish off with a Gunblade, or just get Will and grab Gunblade as a 6th item or to replace your Will. Well, just some suggestions, that is all.

I hate ap morde builds. U need to be tanky. Always take FoN! Ur skill wont hurt you a bit with it! Spellvamp is ok when you start to shine. U cant be a glass canon. U have terribad ap ratio with skills. I prefere to take FoN, Sorc shoes, if they have some AD i love to take sinfire to hurt them bad with W + Sunfire. Than Hexatech Gun and rest depands on a team. U can take Abysal Scepter to assist your team more and have mr it enemy is caster heavy. U can take Will Of the Ancient if you have a casters in a team so they have bonus ap and spellvmp (and it will be good for you too). Liches is great item with gunblade if you want to carry and **** around a bit. :) I hate rylias scepter. U can take ghost, movement quints and u have movement from FoN. U can be around 430 mspeed wich is good in teamfights. U dont need to chase much. U are best when there are a lot of minions and enemies around you!

Man I gotta disagree when you say that everyone eats up Morde by end game. You just need Force of Nature and a good armor item and you're good to go. Rylai's is the definitive best item, I'm sorry Temzilla, but Mordekaiser desperately needs what he lacks the most, and that would be CC. You should get rid of either Will of the Ancients or Hextech Gunblade. WotA would be the wiser choice to get rid of, because frankly, that item just doesn't suit Morde.

Replace Rylai's with Lichbane, then +1.