Okay, does nobody see the problem with this:
Nasus' Siphoning Strike and Fury of the Sands both apply spell vamp. I'm not going to say it's easy to pull off, but I will say it is a game ending monster.

If you don't allow me to tell you:
Runes: AD, Armor, MR/Level, Spell Vamp
Spells: Smite and Flash/ Cleanse
Masteries: 6/11/13
(CDR and minion damage; health/level, minion reduction and damage, armor, health; mana regen, 1 point move speed, summoner cooldowns, mana/level, lifesteal/spellvamp)

End game there should be a Hextech Gunblade among your items.


Still don't get it?
Mercury's Treads with furor or alacrity
Iceborn Gauntlet
Frozen Mallet
Guardian Angel
Hextech Gunblade
Warmog's Armor

62% health return on Q, survivability without stacking armor or magic resist in team fights (only need about 150/100), huge amounts of cc, 1.25 multiplier as an AOE with potential infinite damage that you charge up by farming in the jungle early game.