HI, I'm MrBlueZ, I play on EUW and I'm a Gold V Top Lane main. I play lots of champions, but as you can see thanks to my elo, my skills aren't that good but I have a bit of knowledge into items/runes/etc..
This is my first in-depth guide and I want to show you guys how to play this unpopular champion.
The new Yorick helped me to cilmb the entire elo hell from bronze 5 to silver 5. I have 73% winrate with him as you can see on OP.GG.
In my opinion this champion is very strong in low elo because is quite simple to play and bronzes don't really know how to deal with him. WIth new runes is actually a decent pick also in higher elos.

PROS

TANKY STRONG EARLY GAME NOT SO HARD TO PLAY AWESOME SPLITPUSHER REALLY GOOD AT LOW ELO

NO CC NO MOBILITY BAD LATE GAME/TEAMFIGHTS

CONS

In the early game Yorick is really strong, you should push yor enemy under his tower in orded to make his farming harder, poke constantly him by spawning Shepherd of Souls with your Last Rites, then Mourning Mist on your opponent. When you reach level 6 you can try to all-in your opponent by doing the poke combo while summoning your Dark Procession and then casting your Eulogy of the Isles. Remember that Last Rites reset your autoattack's timer: always land an autoattack then cast your q for a free auto on your opponent.
Mid to late game I recommend to not group with your allies because Yorick is not good at teamfighting. Just splitpush and take as many towers as you can. Always try to take rift herald: enemies can't stop your push when you have rift herald plus your Eulogy of the Isles; Zz'Rot Portal can help you too.

Yorick is really strong vs melee champions with no mobility. Can deal with mobility melee champions but suffer versus ranged champions.
You can see some matchup difficulty over there.

Yorick's Innate is Shepherd of Souls, Yorick raises a Grave for every enemy champion and any 10 non-champion enemy that dies near him, as well as for every enemy he kills with Last Rites.

Yorick's Q is Last Rites, it is an empowered autoattack that always spawn a Shepherd of Souls, it applies on-hit effects and it also resets Yorick's autoattack's timer. This is why Trinity Force/ Iceborn Gauntlet is really good on him. You max Last Rites first because is your main font of damage.

Yorick's W is Dark Procession, it is a wall which block enemies inside it and let Yorick and his allies to pass throught it. The wall can be destroyed but leveling it up increases its hit points. Sometimes is useful to max Dark Procession second if the enemy team has no mobility.

Yorick's E is Mourning Mist, it is a cone-shaped skillshot with a pretty good range, it deal % enemy's healt as magic damage, slowing and marking the tagert, when an enemy is marked, Shepherd of Souls will target him and Yorick and his allies gets a movement speed buff when running towards them.

Yorick's R is Eulogy of the Isles, when activated Yorick summons the Maiden of the Mist plus 4 ghouls. The maiden deal magic damage and his health scales with Yorick's hitpoints.

I recommend to max R>Q>W>E when enemy team has lack of mobility, and R>Q>E>W when enemy team has some sort of dashes or blinks. Always Start with Q Last Rites, you should take Mourning Mist for some good poke at level 2, but if the jungler wants to gank you take Dark Procession instead.

Always use Teleport and Flash, there is no reason to take other summoner's spells. You need the Teleport because in the mid to late game you need to splitpush while having a map presence. You also need Flash, because you know, flash is Flash xD.

So, the new rune system buffed Yorick so much, even because now your Last Rites works on turrets and this synergizes so well with Sheen and Demolish. Always take Resolve tree as the main one. First of all ALWAYS take Grasp of the Undying as keystone, then i reccomend going Demolish because it helps you a lot for splitpushing. The next chocie is situtational, overall Conditioning is the best one but if you are going to play in an early game ad/ ap matchup and you want to be safer then take Iron Skin/ Mirror Shell. As secondary tree i usually go for Precision and then i take Triumph because is really strong on aggresive picks and coup for helping a bit with damage. You can also go for Sorcery and take The Ultimate Hat which is really helpful because of your high Eulogy of the Isles CD, then you can take Transcendence which can be really usefull for both builds. With the first one you will get the 40% CDR, the second one you will overcap you cooldown reduction limit but you will get some free AD which is pretty good.
Feel free to choose other things situationally.

In this guide I'm showing two ways to build Yorick

But first let's talk about starting items.
I usually take Corrupting Potion because it gives you Sustain and a bit of damage which is useful in trades. If you are versus a bad matchup like Pantheon or Kennen start with Doran's Shield, Doran's Blade is good but Corrupting Potion is just better.

The first one has as core items Trinity Force, Sterak's Gage and Zz'Rot Portal. The Trinity Force gives you a lot of powerspike when completed, it helps you to push towers thanks to the Sheen proc as 200% of yor base AD, and is a really good duelist item, Sterak's Gage empowers your sheen proc, gives you more damage and his passive is very strong, Zz'Rot Portal, isn't as good as he was before because it has been nerfed in preseason 7, but I still always build it thanks to its hybrid resistances and its active still helps you push towers faster. Always use this build except vs heavy tanks or full AD team comps.

Sometimes I swap Sterak's Gage with Titanic Hydra this will be useful if your team does not have a lot of waveclear. After core items you should buy two tank items; I highly recommend Spirit Visage if you need some MR, his passive sinergyze with your q heal and it also gives you more cooldown reduction, if the enemy team has a DoT AP champions like Rumble or Swain the Adaptive Helm isn't a bad buy also because he recently got buffed twice. As armor items both Dead Man's Plate and Randuin's Omen are great, you can also take Thornmail vs AD heavy team comp.
Obviously Take Ninja Tabi or Mercury's Treads depending of what you need.

The other way to build Yorick is with Black Cleaver + Iceborn Gauntlet as core items. Only use this build if you are versus full ad team comp or vs tank matchups. Your Black Cleaver will help you to shred tanks armor, in this case you will take Iceborn Gauntlet because Black Cleaver already has the Phage component, so with Trinity Force you will waste the passive. I recommend buying Sheen and then complete your Black Cleaver. This build is also strong vs full AD team comps because Iceborn Gauntlet gives you 65 armor and you don't need to buy Spirit Visage because you already have 40% cooldown reduction.

After core items I usually build Titanic Hydra and Zz'Rot Portal. Then you can still get a tank item: Spirit Visage and Adaptive Helm they both gives you magic resist but they also gives CDR which you don't need because is already at 40%. As armor item you can get one of this: Dead Man's Plate, Randuin's Omen or Thornmail. It depends of what you need.
Obviously Take Ninja Tabi or Mercury's Treads.

P.S. In the build showcase I put some other situational items, I never buy them, someone does, you can try them if you want.

PATCH 7.24

- Yorick's base ad decreased to 62 from 65, not a big nerf.
- Coup de Grace and Triumph got a samall nerf too.