Thunderbringer

Skill Build1 – Chain Lightning
2 – Lightning Rod
3 – Blast of Lightning
4 – Blast of Lightning
5 – Blast of Lightning
6 – Lightning Storm
7 – Blast of Lightning
8 – Lightning Rod
9 – Lightning Rod
10 – Lightning Rod
11 – Lightning Storm
12 – Stats
13 – Stats
14 – Stats
15 – Stats
16 – Lightning Storm
17 – Stats+
22 – Chain Lightning+
Justification / Modifications:
Get one level of Chain Lightning early but don’t use it to last hit unless you are getting outdenied heavily (for example versus a soul stealer)! You don’t have the Mana to use it for last hitting. Use it to have a second way to proc Lightning Rod instead.
I don’t bother with maxing Chain Lightning, but you can if you like to. By the time you get level 14 (lvl 4 CL) its kinda ineffective for farming already.

Lane Starting Items:
Upgraded Flying Courier, Runes of the Blight, 2x Mana Potion

Core:
Bottle >> (Power Supply >>) Marchers >> 2x Talisman of the Exile >> Wards of Sight

You don’t need stats to start of as your last hitting is pretty terrible anyways. Eiter drive the enemy back so you have free reign over the creeps or use level 1 Chain Lightning for Last Hitting as explained above. You can start with a naked bottle but imo it is a lot better to get the flying courier who can bring you mana potions and who can easily refill you bottle at the fountain.

After Core:
Ghost Marchers >> Kuldra’s Sheepstick >> Sacrificial Stone

Why Ghost Marchers? His Move speed of 295 is among the slowest in the game. To gank he needs to come into range for his Blast. Also Blast has a very short cooldown and the boots allow you to effectively chase someone for that last cast. And finally the +damage helps your farming a lot more than attack speed.
Keep Buying Wards or at least help buying them.
Then get Kuldra’s Sheepstick to stay viable in late game. Don’t get SotM, ever.

Information:
Roles: Nuker
Prefered Lane: Mid
Difficulty: 2 – Easy
Farming capabilities: 3 – Decent (chain lightning)
Item dependancy: 1 – Very Low
Power:
– Early Game / Lane Control: 5 – Very Strong (Heavy Nukes)
– Mid Game / Ganks: 3 – Medium (Decent Ganker, Brings his damage to team fights)
– Late Game / Team Fights: 2 – Weak (“Scales” somewhat into the later game but is much less effective)

30-Seconds-Guide:
– Start nuking with Blast of Lightning at level 3. If you run low on mana bring more Mana Potions with your flying courier.
– Get a bottle asap, use the flying courier to check runes and send the courier to refill the bottle if you don’t get enough runes.
– Last hitting and denying is secondary with Thunderbringer. Play aggressive and keep up high pressure.
– As soon as you have ghost Marchers get ready to gank other lanes.
– If there’s an invisible hero that’s in the area, use Lightning Blast on a random creep to reveal the area. If the invis player is bad, chances are he won’t even notice.
– Blast of Lightning has a Ministun.
– Use Lightning Storm before you die, even if it doesn’t kill! Better even, use it at the start of teamfights to prevent Portal Key surprises and to give you an early advantage.

Counters:
– If you lane against Thunderbringer get a Mystic Vestment ASAP! Upgrade it later if you can/need to.
– Use your courier to bring a lot of regen items to your lane. If you need to go back to heal more than once early game he will outlevel you and you will have even more problems.
– Consider skilling stats if you can with your hero.