My Morde Guide.

First Pick morde

Runes
9x Magic pen Marks
9x Health seals
9x CDR glyphs

3x MS quints

Masteries
9/21/0

Summoner spells
Ghost (Lets face it people run away from me and i like being able to run into team fights like a mad rambo)
Ignite (Ult+ignite)

I usually start off with a Regrowth pendant then i start to look at peoples items and stats to figure out if i need armor or magic resist then continue to either get magic pen boots if they are more AD or get another regrowth pendant then level 1 boots.

For laning I just dominate like a boss getting all the creep i can keeping up my shield and getting some good harass in (Remember to not be a herp durp)

Once you start being a tanky boss get like a rylais for maximum rape. Slow people and be healthy? hot damn plus more dmg on your already fairly high dmg spells?

So if theyre all like ad bosses but theyre like burst types i just roll with a sunfire. if theyre straight auto attack thornmail.

for magic bitches i get a FoN and maybe an abyssal for max ap and mr and mr reduc deliciousness.

and once the game has been all cool for like a million years and you got like a million CC get a hextech gunblade shits awesome. your Q gets shit from ap and ad. PLUS its a nuke/slow and all your shit gets spellpen too so youre like regen like a boss if youre like constantly raping shit. and if the game is like SUPRA LONG get a deathcap and its gg
if youre a boss like me

OH and also if they have a ranged carry FUCK THAT BITCH UP WITH YOUR ULT ASAP. Why? cause a ranged carry fucks shit up. people forget mordes ghost sometimes. and if you have good ghost control you get pentas. hahaha sivir ghost...