I am by no way an expert, I was simply playing around with the builder and thought I might as well post this in order to get some feedback.

I love Yorick, he looks awesome. I play him as often as I can and am considering making him my main. I apologize for the lack of coding, but ain't nobody got the item for that.

Unholy Covenant: Our passive, we do more damage and take less damage for each ghoul we have out, so when engaging you should have as many out as possible.

Omen of War: This does great damage but I max this last, because we get more use out of our other skills.

Omen of Pestilence: Our slow so we can close the gap, hence its the second skill we max.

Omen of Famine: Our first maxed skill since it gets us incredible sustain.

Omen of Death: Well I use this primarily in team fights, or if I have engaged 1 or 2 enemies and looks like I won't survive the fight. Hence I use this skill to get more damage and if I die, at least come back as a zombie and try to kill my primary target(the squishier one if two)

Our Core:

Manamune: This our primary source of damage, we do more damage the more mana we have, however we build this second. Our first priority buy is the Tear of Goddess and it takes a while to build up the stacks. Once it upgrades to Muramana there is no stopping us!

Iceborn Gauntlet: Our secondary damage item but it does more, it slows, gives us armor, cooldown reduction and gets us some damage. Hence we finish this first.

Frozen Heart: Our final Core item, this gets us everything we need armor, mana, cooldown reduction and the passive kicks ***.

Boots:

Ninja Tabi: Ideal against AD heavy items, I generally get this unless I'm going top

Boots of Swiftness: Ideal against teams that have a lot of slows and not many other kinds of CC.

Mercurial Treads: I only get this if I am going top and they have any CC other than slows, if jungling I do not get this since Juggernaut fulfills my needs and gets me more.

Jungling:

Stalker's Blade: Many opt for Trailblazer but I say we don't need it, however we do not need the AoE, what we need is more CC and ways to close the gap.

Juggernaut: Our ideal jungling upgrade, I do not get this till my core is complete. We get the HP we need, cooldown reduction and a whole lot of Tenacity. I do not stack this with Mercurial Treads since Tenacity is multiplicative not additive.

Warrior: After finishing my core, if I find that I'm pretty ahead and I do not need the extra HP, I'll go for Mercurial Treads and get Warrior instead. Cooldown reduction, armor penetration, and some damage.

Our Final Items:

Righteous Glory: I prefer this over Warmog's. I get less HP and regen from it, however it gives me mana which means more damage and an active for amazing chase/escape power for the entire team.

Frozen Mallet: This gives us no Armor or MR, but it gives us HP, damage and a slow on each hit, so its upto you what you want out of your final items.

Spirit Visage: HP, HP Regen, MR, Cooldown Reduction

Banshee's Viel HP. HP Regen, MR, a great shield every 40s

Thornmail: Armor and damage reflect only for AD heavy teams