Engineer

Skill Build
1 – Steam Turret
2 – The Keg
3 – Tinker
4 – Tinker
5 – Tinker
6 – Energy Field
7 – Tinker
8 -The Keg
9 – The Keg
10 – The Keg
11 – Energy Field
12 – Steam Turret
13 – Steam Turret
14 – Steam Turret
15 – Stats
16 – Energy Field
17 – Stats+

Justification / Modifications:
Steam Turret at level one to place at the rune. Don’t level it up further as you will first need some items to make it viable.
Tinker vs The Keg: As of recently i prefer Tinker for the reduced Manacost and Cooldown on Keg and for devastating early Tower Pushes. Level 1 Keg with Level 4 Tinker costs 56 Mana and has 7.9 sec Cooldown (same Pushback and Cast range, 150 less damage and 0.75 sec less stun). Level 4 Keg with Level 1 Tinker costs 130 Mana with 14 sec cooldown. More than twice the mana and 77% increased cooldown for 150 damage and 0.75 sec stun. This is not even taking in account all the other uses of Tinker. If you can set up high pressure in your lane with a very agressive lane partner max keg first. In all other cases go for Tinker first.

Lane Starting Items:
Monkey Courier, 2x Runes of the Blight, 2x Mana Potion, 2x Minor Totem

Core:
Power Supply >> Soulscream Ring >> Ghost Marchers

Power Supply is pretty strong as your combo will need a lot of burst mana. Also just a few Charges will allow you to cast a Keg with 0 mana. Ghost Marchers are viable for chasing with Keg (it’s an amazing chasing skill). But you can get Steam Boots if you play more Carry heavy.

After Core:
(Nullfire Blade >>) Frostburn >> Charged Hammer >> Geometer’s Bane >> Frostwulf Skull

Get a Nullfire ASAP if your team needs to counter Hellbringer, Hammerstorm or Jeraziah. Frostburn is a staple choice for most carries. Gives you pretty much all you need including a slowing turret. Charged Hammer then turns your turret into a true machine gun. With lightnings.
After that disassemble your Frostburn and create Geometers from the Firebrand as well as Frostwolf from the Icebrand.

Alternative Items:
– Portal Key: If you have no initiation. You can be a decent initiator but you need the Key for it and there are a lot of heroes who can do the job better than you. This is why Portal Key is not core.
– Barbed Armor / Shrunken Head: Get this if you need to initiate.
– Astrolabe: Especially in combination with Barbed Armor if you go for a supportive playstyle.

Information
Roles: Semi-Carry, (Initiator)
Prefered Lane: Any
Difficulty: 3 – Medium (Not as trivial as it might seem)
Farming capabilities: 3 – Decent
Item dependancy: 3 – Medium
Power:
– Early Game / Lane Control: 3 – Medium (One of the best attack animations but low damage. Keg is very annoying.)
– Mid Game / Ganks: 4 – Strong
– Late Game / Team Fights: 3 – Medium (Can be stronger if farmed well, but is not a Hard-Carry)

30-Seconds-Guide:
– Your basic combo at leevl 14+ if an enemy is in range: Throw down a turret ahead of you, use Energy Field and then cast Keg to push the enemy inside the energy field in range of the turret. If he already is inside wait for him to run out, then Keg him back in. If he fights, Keg him out at ~30% hp.
– Energy Field has a low cooldown, use it every fight!
– Throw down a turret (if maxed) before casting Keg if the Mana allows it.
– Use turrets in the forest to see incoming ganks (level 1 turrets are fine).
– Having Tinker maxed over Keg makes Keg very spammable.

Counters:
– With Shrunken Head on you can ignore Energy Field. If you play a carry get Shrunken Head versus Engi. (Not that it is only good against him…)
– Don’t let yourself get kegged into an enemy tower. This is very dangerous early game!
– Level 1 Turret only has 500 attack range (increasing by 50 every level). Quite a few heroes have 550 or 600 attack range and thus can take out level 1-2 turrets without getting hit. Easy Money.