Sustained Vulcan

With this build you are very tanky and with the early Warlock's Sash you are even able to make a lot of damage over the game. Vulcan is not a killing machine, he is damage over time. Anyway, with this build you can get up to 50.000 player damage + 60.000 creep damage (Arena Sample) and win games!
I played this build for all modes: Arena, Conquest, Domination and Joust. Vulcan is great in Domination, so here i play the Build 3: Sustained to early Damage *Hot*

My Vulcan starts with Reinforced Boots to be tanky in the early stage of the game. He need this, because i always want Meditation in addition, so no money left for Healing Potion. We just have to click on two items in the item shop (both under recommended) and can start in the game instantly.

In Arena and Dominiation you want to start very early to place both (!) turrets directly in the mid. Port back after that, we hope that the enemy has to destroy them or your own team defend the towers while you get your mana back at the startpoint.
You come up with the minions and try to make damage, you can place your turrets again and also try to avoid damage as good as you can. You can place your turrets 3-4 times using Meditation, then you want to port back and buy last boots + healing potion(s). I try to watch out for my turrets, so that my Meditation should be enough mana for the next stage of the game.

Same principle, you place your turret at a spawn point in the jungle and port back to restore your mana. Back at the camp you and your team get the camp and go for a lane. I also do this build in conquest and do an extra port just for healing potions (very less money on the start atm).

Warlock's Sash is the perfect item for Vulcan, it gives you Health (need for the turrets and yourself), Mana (always needed with Vulcan), Magical Power and you can farm stacks (+2 Mana and .5 Magical Power per stack) - the stacks even stay after dead.
You want the stack items early as possible, but i don't recommend to buy it as first item. The famous Hirez worker Bart is playing like this - but Reinforced Boots are better in the early game. Maybe you do the boots 2x and then begin directly with Warlock's Sash (compare with Build 3), when you have this 3x and farming stacks, you can buy the last boot.

My Vulcan loves Sovereignty, this is the best non-stack tank item for him. You don't want to have many stack items, because a game is usually over in 20-30 minutes - this is not enough time to farm that many stacks. With 3x Sovereignty you will notice a good tank effect, now you can stand against Loki or a Xbalanque.

Void Stone is also a very good item on Vulcan, gives you Magical Power / Magical Protection and reduces the Magical Protection of your enemys. Now you are also able to stand against heavy magical damage. The tank part is done, you don't need any more protection.

Get Rod of Tahuti and Obsidian Shard to let your enemy feel the pain. Before you was very annoying, but now you get dangerous. Try to catch the player with less protection (caster / supporter) in your ultimate.

Try to hide your Inferno Cannon, protect it with the Thumber if necessary. Place it always in flank of the enemys / creeps. Inferno Cannon does damage on one target, Thumber does AoE (Area of Effect) damage - both turrets should place next to each other. Sometimes you need to push with the Thumber, sometimes it's better to place the Thumber a bit behind the Cannon.

When you try to run away from an enemy, place the cannon in your run direction. The enemy has now the choice to follow you and get damage or to destroy the cannon first, while you can escape.

The Thumber slows other players, use this to catch enemys that want to escape or to slow down them when they're chasing you. The Thumber is great for tanking towers or to initiate team fights.
Try to run forward, place the Thumber behind the enemy and use backfire to jump back. That's a pain in the *** for the enemy, because he dont expect Vulcan to come near him - then he got shotted by the backfire and after that he have to clean up the Thumber behind him while Vulcan can do work on him.

Use your backfire to escape (best on Hades, target him and backfire out of his ultimate) and to kill low HP player on a 20 feet range. Backfire does also damage to all enemys / creep standing in that range, so it's also usable for creep waves.

You can trigger your ultimate before you place your cannons. Trigger it and run into the enemys (your ultimate gives you speed - you can also use it as escape) and place your turrets there. I have fun to break a strong group of enemys by this. Try to be a pain in the *** for your enemy and not to die by this action - if your timing was good, the damage dealer in your team will do the rest.

Shoot one or two guys with backfire and then go out. If you did a good attack, don't let it ruin by killing you or your team. Back up, retreat, be careful and prepare the next push.

I don't recommend a "perfect skill sequence", i would also not blame anyone for using the auto skills. Most of the time, people do it 4/1/2/3 - so you skill the cannon first for damage, after that the Thumber and your ultimate. You can also do 4/2/1/3 - so you will have a better Thumber which let you stay in a lane for longer time and you can better tank jungle creep.

With this build you are very tanky and with the early Warlock's Sash you are even able to make a lot of damage over the game. Have fun!

You want to have fun with Vulcan? This is not a guarantee to win, but 100% fun. Here is what we do: we reduce our cooldowns and get extra movement speed with Boots of Celerity. The book of Thoth is not cheap, but it's the best item for what we planning - gives us some Magical Power and tons of mana + stacks. Next item is Chronos' Pendant, now we are on 40% cooldown reduction - even though only 35% of them are counting. Don't get any more cooldwon reduction!

We have the mana and the extreme short cooldown, so let's get the damage with Rod of Tahuti and Obsidian Shard. I recommend Bancroft's Talon at the end.

Pro
With this build you will do a lot of damage and in the endgame, you will always have mana for powered turrets.
Contra
But those turrets will not live for long and you are very weak. So, try to stay out of range.

I love this build - try it in domination, you will be amazed how effective this is. We want the stacks very early, thats why we purchase Warlock's Sash first. So, in the end of a domination you are up to 90-100 stacks.
I personaly like the tank boots more than boots of celerity, you will miss the hp restore - but it's up to you.
Next is Obsidian Shard, it's cheap and you will get magical power and penetration. After that you take Rod of Tahuti to increase your magical power even more.
I like a tank item for the next slot (because the damage output is good enough at this point), for normal i take Sovereignty and Bancroft's Talon or Void Stone.

Pro
This build is perfect for Domination, but also very good on the other modes.
Contra
A good tank / damage combination with focus on your towers will may conter you.