Hey guys
in my opinion, I'm not a high skilled pro-gamer - but when i take Heimerdinger i usually rock the **** out of the game!
In this guide I want to share my gameplay with you.
I play Heimer mid lane as an rocket-spamming harras mashine.

And - please - dont be angry with my english, that's the first time i used it that much after leaving school 4 years ago xD

Pros:
Hard to gank
Has a scout ( CH-1 Concussion Grenade)
A lot of area dmg
Great pusher
Very high range


Cons
Sooooooooooo slow. You cant take enough o's in it.
Dependent on blue if you have a hard pushing opponent.

I usually take:
- Flash Brings you in, brings you out - must have spell for almost every Champion.
- Teleport Heimer is soooooooooooo slow. Ganks usually only can be done with this spell. Also it brings you fast back to lane whan you had to go back or you died.

After an awefull game today i also will pick Cleanse when i have to play against a Vejgar. He always placed his stun just perfect and after early game which i just "won" with a few more minions than he had, he just nuked me out of my boots.

If you say you dont need Teleport you can pick Ignite for sure.

21 Dmg. We need dmg. You just have to do that.

0 You do dmg to the enemies, but they not to you because you will try to stay out of their range/they dont want to come in your range because of that dmg that you deal. So we dont need tanky masteries.

9 You usually have to work without blue buff in early, so that manareg is perfect and an improved recall/teleport/flash is all that we need. And Runic Affinity is great later when you get your blue buff.

Runes are here to push your stats in the early game.
Red: Greater Mark of Magic Penetration The penetration does more than the +AP that Greater Mark of Ability Power gives you.
Yellow: Greater Seal of Armor But I'm not really sure about this Seals - I had the dodge runes in it but they got removed so i bought armor as a cheap substitute. Maybe I'll take the Greater Seal of Endurance, I'll tell you when i know more about that.
Blue: Greater Glyph of Ability Power Clear, more AP
Qintessence: Greater Quintessence of Ability Power A lot of more AP

You will deal good dmg on lvl 1 (46AP with Doran's Ring) and minion-/ gank-auto-hits that lands on your big brain wont feel that hard.

Your passive:
Techmaturgical Repair Bots It's a pitty that you can't see them ;)

H-28G Evolution Turret (Q-Skill)
Helps you pushing, stops every pushed minion wave and can turn around every team fight.
On lvl 3 you can build 2 of those beasts and maxed they do area dmg. When your Ulti is activated they gets healed up to 100% and do slowing freezy dmg.
There are many things to know about them:
Remember that fresh built turrets have more attack speed than turrets that stood in the field for a while. If you need to go back, make sure a turret is near the lane. You'll still get experience points and maybe some last hits to minions.
They give you lots of area control so you can come out ganks very easy or you place one as a ward into the bush. I'd do that just in emergency situations.
But they also are easily distroyed and than one of your abilities is useless for the next 25 seconds. So you have to protect them - make it as painfull as possible for them to hit your turrets!
Also they can be useless in a teamfight very fast when they are placed too early and the fight moves out of their range.
When Heimer is near a damaged turret, it regs life with his passive. But thats so slightly, it's not worth to risk something. If the enemie focus your turret and you have no manaproblems, build a new one, so he can't get the gold for the kill.

Hextech Micro-Rockets (W-Skill)
Your Bread'n'Butter ability. The range is just evil. It shoots 3 rockets in the face of the nearest 3 enemies. In any possible moment you get you have to shoot one of them into an ugly enemy face that comes too near without enough minions. Enemies have to play very passive and will lose minions on the tower otherwhise they will eat tons of dmg and have to go back.
With acitve Ulti you shoot 5 rockets so you deal a lot of dmg in every team fight.

CH-1 Concussion Grenade (E-Skill)
Blind, stun and lots of dmg. Very cool. If you can land it right. It flies very slow so you have to time it very good. If you learned the feeling for this, you can kick your or some teammates *** out of some bad situations. In teamfights you can knock out the AD carry. If it dont stuns, no problem it blinds them too. You also can threw one into a bush to see into it. When Ulti is active the grenade flies faster. Later you wipe minion crowds with 1 granade away from the map.

UPGRADE!!! (R-Skill)
Name speaks for its selfe. Makes every ability stronger. Very cool passive: reduces your cool downs!


I often have the situation: The enemy just needs 1 more Rocket to die. But there are allways 3 minions left and when not, he goes out of my range and regs his life. So what can we do? It took soo much time that i got the great idea that i could use my ulti to send more rockets - and there you go, more money in the bank. Sometimes the simple things takes the longest time *blame on me* xD

The item buy is very important all over the game. If you dominate early gaming you will usually dominat the whole game. And 50% of that will be the choosing of your items.

@ top you see what i would've bought if the enemies didnt quit a lot of time before.
What you cant see is my 1. item. And.. it's.. Tadaa: Doran's Ring - what a surprise!
Manareg, health and AP, all that we need for a chilled early.

When you have an easy farm, means you've almost got every minion and a few kills and you didn't need to go back yet:
You buy Needlessly Large Rod and Boots. This huge mountain of AP gives you lots of power and you will need movement speed to get faster in positions for ganks or back to the lane. But the others will do some dmg now, too! So you'll need life, which we get with Catalyst the Protector. Than we finish the boots to Sorcerer's Shoes. More speed, more dmg that crashes through their ressistance. Simply nice. Than its on you: Do you feel you need more dmg or more life? But for sure, the next 2 items will be Rabadon's Deathcap and Rod of Ages. But when Rod of Ages is done, health points will be enough. After that point, you kill minions with 1 granade. For more fun, we need more dmg that you'll get with Zhonya's Hourglass. Much AP, some armor makes you more tanky and you'll get more focussed so the active of Zhonya's Hourglass is perfect to laugh at them and watch them die. Heimerdinger is soooooooooo slow. So I decided to get Lich Bane. It gives more speed, magic ressistance makes you even more tanky, another huge cake of AP and +dmg to your autohit. Do i have to explain more? And if the game still isnt over yet (because teammates fed or only your lane enemy lost his lane against you) you sell Doran's Ring and buy Guardian Angel. The enemies will do dmg - and they will try to hit it in your face if they aren't that stupid. So more armor, more magic ressistance and a revive that allowes you an evil-laughing comeback will send them right back to their base.
You can also switch the last 2 items if the game needs it.
Than it could look like this


If you have a strong opponent on your lane:
Especially against an annoying Kennen or a good Brand or Cassiopeia (I relly hate Cassio -.-) it can be very usefull to buy the boots first to dodge their attacks and Catalyst the Protector to stay on lane as long as possible.
Also if they gank you a lot and if they gank good, it'll work better if you take life before dmg.
So it could look like this:But I always feel useless without that dmg from Needlessly Large Rod.

If you think your life still isn't enough you can change Lich Bane with Rylai's Crystal Scepter.
And if you think you need more AP ressistance than armor you could switch Zhonya's Hourglass with
Abyssal Mask

Rocket launcher.. But why a Turret at first?
It makes farming a lot of easier and I use it as a puffer for aggressive player that pushes hard. You'll geht almost every minion and won't lose any to your tower. And its a good back up if you get ganked. Rockets are too expensive in mana to do the job with them in the early.
When game starts I run to my tower immediately und set a turret into my lane and than I cover blue for the jungler. I set the turret near to mid but not directly, so a Xerath for example can't hit my turret+minions.After the pull I have full mana but a turret in the lane.

When the 7th minion is dead you get your rockets - and the fun begins! But dont push with autohits. Rockets will push enough. Just last hit the minions and if there are only 2 minions and your lane opponent left or in range shoot their ***es up. And if he stands allone, shoot him up! And if ganker comes, let them fly! In every second you can do, shoot rockets to enemy champions. In the first lvls you have to watch out because of your mana. A Heimer without mana is as usefull as one of the little golems. And usually the jungler needs the blue to makes it faster so you have to work with that mana that you got. It's only training to make it.

@ lvl 3 I do a skill point to the granade. And I only use it when i really need it because of the mana costs. Usually when I get ganked. Stun, if its too close, do a flash and you are safe.

This is very powerfull in the early gaming and you will harras almost every enemy you can get. Even this alltime feared and often banned Kassadin was so bad underfarmed after early, he never really made it back into the game. He farmed a lot in late game but sucked so hard in the teamfights before.


And than after lvl 3 the priority is on: first , second , third and last but not least CH-1 Concussion Grenade.

Mid Game begins when the first get lvl 10 or higher and the first tower is falling. Magic time. Lanes will be left and more ganks are for sure. Because Heimer is sooooooooooo slow its not such a good idea to leave your lane and run to another. If you have a good farm, go on. But watch out if there is a little fight in the river - go there, help some teammates coming out a bad situation or help kill. If you see there would be a good gank - you got your teleport! Port, kill, if it's allowed go back to base, shop, back to lane, farm. Now you can ask for blue buff and get it as often as you can.

Lategame is a very very explosive feeling. Both teams waits for the others to make a mistake, for a chance to start a team fight.
Your job with Heimer? Before team fight starts: Rockts. Spam them all the time, every health point you can shoot away is it worth. If you dont have blue watch out for your mana that it isnt to low when the party is freaking out.
When it explodes, you stay a little behind, try to hit the AD carry or another strong dmg dealer or annoying support (like Janna) with your grenade and for sure spam your rockets. A few seconds later most ultis will be done and now its your turn, because the chance that your turrets will be nuked down is low now: You have to come straight into it. Activate your , place one turret, fire a rocket and a grenade. The teamfight will move to another place and now you set your second turret. Dont wait too long for it, only a few seconds.
Also when the enemy team runs into a trap of yours, dont set them immediately. You also have to look if you will need them to slow the enemies for
- help your team to escape
- hinder the enemies to escape
Now there are 3 options.
1.: You died. After you respawned swing your *** as fast as possible to the place where it's needed.
1.1.: Your team won: Port to a minion/ward and help push
1.2.: Your team lost: Defend towers/inhibitors as good as possible.
2.: Your team lost but you still alive: help other survivers and defend towers/inhibitors. But don't let you kill because the others dive you. When they are too strong go back - thats better in any ways.
3.: You won the fight: help push. Your turrets do a lot of dmg to towers. A tower focus your turrets like a minion, so you can set them to let them tank, so no one of your teammates takes dmg from the tower.
Or if your team decides to do baron or dragon, help there. You can set your turrets and let do them the work.
A Tip: If you are @ the tower before the inhibitor: place the turrets between tower and inhibitor, so after the tower is down your turrets can shoot the inhibitor down.

So I hope I made a guide that's not too long but every important thing is in it and you can understand and learn from it.
Never thought it would take so much time -_-
But I'm pretty proud of it :D
Please leave a comment, I'm open to critics - I'm sure I still can learn some things.