Hi! I'm RettsuDansu.

I picked up Jayce a while ago and now he's one of my main champs. His kit for so long has entertained me on the Rift and I wanted to share a build for Season 6 I found while experimenting.

When someone says Jayce, no one thinks tank. People usually find him to be a bursty damage dealer. When it comes time to team fight, he, if he screws up, can get utterly destroyed for the fact, quite frankly, he's Jayce. He's not innately a tanky champion.

Always build appropriately for your opponent, but if you need so more health on your team, definitely refer to this build to help your itemization for a bulkier version of Jayce.

Tanky Jayce

Pros

Won't get popped as easily in fights / Does better in prolonged fights
Has great sustain + utilizes AP damage
Still has the power to pop squishies + has Jayce's utility


Cons

Does not have the full damage a Jayce could be building
Build path doesn't utilize Armor Penetration early on if that's important
Falling behind while using this build means relying on your team for more damage

The phrase, Tanky Jayce, already raises some eyebrows.

Hextech Gunblade
With the new Hextech Gunblade, all damage that Jayce puts out turns into health. That includes his magic damage dealing moves: Lightning Field and Thundering Blow. This healing also includes his Shock Blast (even when used in conjunction with his Acceleration Gate!), and the rest of his AD based abilities.

Why build an effectively AP Item on Jayce?
Jayce benefits from both AP and AD. Lightning Field scales 1 to 1 with your AP (It says 25% per second, meaning if the full duration is inflicted it's 100%), and as such will deal as much AP as you put into it. There is nothing lost when buying the Hextech Gunblade or any of its component items. All of it will contribute to your damage and sustain. Also, both forms of damage contribute to your almighty Thunderlord's Decree . The slow that the Hextech Gunblade brings can even help you gap close with To The Skies! or aim for your Shock Blast.

Why build tanky at all?
With your Lightning Field, you deal damage by standing next to someone. Not being able to deal the full amount of damage because you don't have enough health to continue a fight doesn't allow you use it to its fullest. The usage of Hextech Gunblade and Sunfire Aegis remedy this issue, giving you sustain, health, and some extra magic damage on top to continue a fight. At that point you can use your Lightning Field, chase with To The Skies!, hit them with your hammer a couple of times and finish with the percent based magic damage of Thundering Blow or even just change into your cannon form and snipe a fleeing target with Shock Blast. The good news is all of your moves (except for your Acceleration Gate, of course), will deal damage and heal you.

Choose:
Teleport
Great usage of it around the map can win games, but poor usage is a waste of a spell slot. The basic summoner spell to take in along with flash, but think about what you will be doing before taking it in.

Ignite
Helps you finish off enemies if they survive your Thundering Blow, assists in aggressive play. You might need this to get the keys kills that allow you to win lane and carry, so think about this as an option as well.

Use:
Flash
You better bring this to the Rift. Gives you offensive and defensive potential. Use it. It helps you position for your To The Skies!, escape, and a bunch of other things.

Ferocity Tree
Fury / Sorcery
Attack speed doesn't heavily benefit Jayce as much as his abilities, but his last hits might seem a bit clunky. This is a toss-up to preference but I feel having more damage in his abilities is more helpful when utilizing your Hextech Gunblade

Double Edged Sword / Feast
This is completely up to preference. I would rather not run Double Edged Sword considering you're building tanky.

Vampirism / Natural Talent
Vampirism works best with the Hextech Gunblade so run it.

Bounty Hunter / Oppressor
Bounty Hunter seems like a better pick. Jayce doesn't have any innate comboable CC.

Cunning Tree
Wanderer / Savagery
Savagery is overall more helpful as it assists in last hitting.

Runic Affinity / Secret Stash / Assassin
It's a matter of preference between sustain( Secret Stash ) and damage ( Assassin ).

Merciless / Meditation
Merciless is a sure pick considering the next mastery.

Bandit / Dangerous Game
Dangerous Game is a very helpful mastery, run it.

Precision/ Intelligence
Precision's free penetration is very much welcomed. Although, this is up to preference if you really want to have that 5% cooldown.

Thunderlord's Decree
I don't care about the other masteries. Run this one! Basically free damage and helps with Jayce's bursty potential.

Hammer Form
Q - To the Skies!
Deals attack damage, scales on AD, jumps to enemy unit dealing splash damage in a small area around landing

W - Lightning Field
Deals magic damage, scales on AP, continually deals damage around you
E - Thundering Blow
Deals % magic damage (Based on enemy champion's MAX HEALTH), knocks enemy champion back


R - Transform!
Switches form + abilities and stats relating to magic resist and armor, applies bonuses from Hextech Capacitor


Cannon Form
Q - Shock Blast
Deals attack damage, scales on AD, shoots a skillshot projectile that explodes on contact to deal splash damage
W - Hyper Charge
Increases attack speed to its max to with an applied damage modifier for 3 basic attacks (at lowest 70%; at highest 110%)
E - Acceleration Gate
Increases movement speed allied champions for a while (including you) when stepping through it, used in conjunction with Shock Blast to increase the range, speed, and damage of it


Which skills do I max first?
I would max Q first for the fact both sides give reliable damage.

It's a toss up between W or E for which you want to max next.

W gives you Lightning Field + Hyper Charge
The draw of W is the hammer form's passive ability (from Lightning Field) to replenish mana from basic attacks improves. Also, your hyper charge starts to become more useful considering the damage increases.

E gives you Thundering Blow + Acceleration Gate
The main draw of E is increasing the percent damage of Thundering Blow. This is really helpful considering you aren't running armor penetration early on (it's dealt in magic damage) and being able to basically knock off 20% of the enemy's health is very impressive.

(My preference is maxing E, but you can go either way.)

Core Items

Manamune
It speeds up the rate from Tear of the Goddess (+1 to +4 per basic attack and expenditure of mana) which you max out your mana pool, and when you max out the mana gain to 750, you will automatically get the Muramana which has active that increases the damage of basic attacks and some spells. A helpful item considering Jayce's heavy mana usage.

Hextech Gunblade
Gives you all your sustain. You should probably start by running either side of it to give you sustain ( Bilgewater Cutlass or Hextech Revolver). Make sure to use them accordingly.

Sunfire Aegis
Gives you armor and health. Will be used in conjunction with your Lightning Field to do some extra damage.

1) Starting Items

Sapphire Crystal + Refillable Potion
Gives some mana to work with, possibly to harass more with your Shock Blast. Starts a part of your core, Manamune, right away. The refillable potion gives you some early sustain in lane.
Long Sword + Refillable Potion
A basic start. You get some early AD and the potion gives some early sustain in lane. The long sword will be used in building the AD portion of your Hextech Gunblade.

2) Manamune

After starting lane, your goal should be rushing your Tear of the Goddess into Manamune.

3) Boots

After your Manamune, stop some time to get some boots.
Although I have some recommendations up there, it should be left up to preference.

4) Hextech Gunblade

You'll be receiving more sustain than from your potion now. You should build one side of the Hextech Gunblade. The sides of it are the Bilgewater Cutlass and the Hextech Revolver. Just make sure you know what to do when trying when healing with either side of it.

5) Sunfire Cape

After your Hextech Gunblade, rush your Sunfire Aegis.

6) Options

At this point you should be done with your core. At this point, build more items thinking about the enemy teams' comp.

Some recommendations would be:
Spirit Visage
Increases healing from Hextech Gunblade, gives you some magic resist for defending from an AP carry, and some more health
Black Cleaver
Gives you health and a method for armor penetration on other tanky champs, helps if you have other attack damage dealers on your team
Randuin's Omen
Gives you health and more armor if the carry seems to be AD oriented


(My preferences are starting Sapphire Crystal, buying Lucidity boots, and starting the Gunblade on the Hextech Revolver side.)

Combos

Make sure you train your muscle memory for these combos. Quick execution is what gets you your keystone proc and all the damage you can do in on your opponent.

Q To The Skies! > Basic Attack > E Thundering Blow
A basic Jayce hammer combo. Brings you close, allows you to hit them once with your hammer (proc-ing the damage bonus from your Hextech Capacitor and also your Thunderlord's Decree ) and then knock them away so you can double back.

Q To The Skies! > Basic Attack > E Thundering Blow > R Mercury Cannon > E Acceleration Gate > Q Shock Blast
An extended combo, utlizing both forms. There are things you should keep in mind relating to the cannon form of your combo. Check if enemy minions can interrupt your Shock Blast (chasing your enemy behind their minions and then knocking them away should give you a clear shot) and make sure your Shock Blast won't make contact without going through your Acceleration Gate (what's the use of the damage multiplier if you hit them too early?).

E Thundering Blow > R Mercury Cannon > E Acceleration Gate
A really basic combo to help escape a sticky enemy champ. Knocks the enemy champ away and allows you to speed off. Doesn't work all the time if they're able to get their crowd control abilities off first.

Things to keep in mind concerning the Hextech Gunblade

Make sure to use its active! Slows are pretty helpful considering you have a gap closer.

If you see a large wave of minions, jump into them with Lightning Field. You'll heal right up considering how much damage you're dealing to each of them.

If you know you're going get cc'd, activate your Lightning Field for some free damage if they decide to keep attacking you.

Tips

Practice your Q ( Shock Blast), wasted mana and possible damage in lane can mean a lot in lane.

If you're able to use your hammer to whack them from where they want to go (like the safety of the turret), use it! If flashing for it while your jungler is ganking means a kill, do it!

Be very sparing with your E Thundering Blow, it can mean life or death and if you switch out to cannon form too quickly or your burn it early, allowing for the person to retaliate leaving you with no answer.

The "Q > basic attack > E" hammer combo, a mere set of basic attacks (maybe done with W Hyper Charge), a combo including a Q Shock Blast and 2 basic attacks, and just standing next to your enemy for long enough with W Lightning Field up can proc your Thunderlord's Decree .

Although it may be tempting, do not always use your E Acceleration Gate + Q Shock Blast combo early game. It'll drain your mana too quickly. A simple Q will suffice when dealing damage and with the Thunderlord's Decree the damage will rack up anyway.

To do the full amount of damage you can do at a time, you will have to cycle through all of your skills, even through the forms. Always keep an eye on when you use your R as there is a sizable cooldown in between going back and forth between them. Getting caught out when you thought you could switch to your other abilities won't do you any favors.

While fleeing from an enemy and using your Acceleration Gate, you most likely will have an open shot while they continue pursuing you. See if you can turn around and hit them in the face with a Shock Blast through the gate as you run. (You will briefly stop to play a shooting animation, so make a smart decision!)

Be careful with the usage of your Thundering Blow. It's a great finishing move because of its percentage based damage, but not if you overestimate the damage it deals and you knock them away before they die.

Always remember to use your Acceleration Gate on your allies as well. Many thanks will be given if you can gate for a friend while they're fleeing from or chasing an enemy champ.

This is actually the first guide/build I've written.

If I've made any errors, need to clear something up, you have suggestions, ect., please leave me a message!
Thanks for reading my guide!