Heimerdinger is a very underrated hero that is almost never played right. With the right positioning and build, you can easily become an unstoppable force. The reason why he's not played right is because of people building him squishy which leads to short battle time in the field. Remember, the number one thing that has to always be on your mind is your position.

Pros:

Tanky
Controlling
Hard-Hitter
Support

Cons:

Slow
Gankable
Hard to Position

The runes consist of:

Greater Quintessence of Health Flat Health Quints: Makes you a lot harder to kill early game and keeps you in lane longer.

Greater Glyph of Cooldown Reduction CDR Glyphs: Helps you get high CDR with your ult.

Greater Mark of Magic Penetration Magic Pen Marks: Gives you extra M Pen early game for your rockets.

Greater Seal of Ability Power AP Seals (Choosing different Seals is optional): Personally the extra AP helps my rockets hit harder early game which gives you more lane control.

I chose 9/1/20 for the: Magic Pen in Offense
Heal Bonus in Summoners Resolve (Defense)
CDR + Exp gain in Utility

Instead of getting Mastermind I picked Summoner's Resolve for the Heal Bonus. Having the extra 10% heal bonus makes you a lot harder to take down when baiting with Heal.

When you start the game with Dingus, It is very beneficial for you to start with a Doran's Ring. After your first ring you buy two additional ones. Doran's Ring gives you the stats you need to control/dominate your lane.

After getting your 3 Doran's Ring and Boots, you now build your Catalyst the Protector. This practically makes you a pain to kill along with Heal (which is only used to bait your diving enemies into your turrets). You then save up for your Rod of Ages and you're now a legitimate tank early in the game.

After your RoA, you now build a Rylai's Crystal Scepter for the added health and slow. After RoA you build either a Zhonya's Hourglass (for the immunity), or a Rabadon's Deathcap for more damage. I hardly reach this point for it is past 40 minutes into the game and if you do your job well they will be pushed in at every lane.

My skill sequences is very different from the rest. I chose not to get the Ch-1 Concussion Grenade and UPGRADE!!! due to the fact that you MUST rush your turrets and rockets.

The Hextech Micro-Rockets is your bread and butter. You should be nearly spamming these rockets every time they're up. Since you're rushing the rockets very early you hit very hard and it makes your opponent afraid to even get near you in the lane. Positioning is key with this spell for you must only use them if there is 2 creeps beside your opponent. Don't underestimate the distance of these Hextech Micro-Rockets for they will go extremely far to get the enemy.

The H-28G Evolution Turret is your protector in the lane. You place the turrets BEHIND your side of the river because YOU DO NOT WANT TO PUSH YOUR OPPONENT IN. I know this is the opposite of what you hear about Heimerdinger but the fact is the further you push your opponent in the more likely you are to die by ganks.
It is pivotal that you do NOT push your enemy in with your turrets and keep the turrets behind the creep wave for when the enemy champion tries to kill you or if you get ganked by the jungler. Also, another reason why you keep them away from the creep wave is because if you do get ganked, run back to your H-28G Evolution Turret so that they will focus on the enemy champions instead of the creep wave which could potentially kill you and not back off your attackers.

The Ch-1 Concussion Grenade is for later in the game. It is a very high skill-based ability since the main purpose of these is to stun your opponent. The reason you want to get these later in the game is because you want as much damage as possible early game to control your lane and to get early kills. The Ch-1 Concussion Grenade does not do very much base damage but with AP they become an effective nuke late game. You always want to throw these if you see:

A clump of enemies
Range/Melee AD Carry
Fleeing Opponents


The UPGRADE!!! ability is all about timing for the active use. The reasoning behind not getting this as soon as possible is because of your mana issues early game. The more CDR you have the more you spam which leads to mana issues. I know I said to spam your Hextech Micro-Rockets and your H-28G Evolution Turret are always on CD, but since your abilities do more damage with only a small increase in mana cost, you wont have to cast them more often early game at low ranks where mana is an issue. Since your skipping UPGRADE!!! at level 6 for more damage; you must play smarter when it comes to positioning. You will not have your deadly slow early game, but if you kite effectively with your H-28G Evolution Turret, your opponents cannot sustain the pain from the rocket spam and turret beating.

My summoner spells may seem to be trollish but it's far from it.

Flash: You obviously want this summoner for escaping a gank or getting over terrain.

Heal: This ability is what makes you unstoppable early game. If you see a gank incoming or an over zealous champion trying to kill you...all you have to do is kite with your H-28G Evolution Turret. As soon as you get below 25% health you pop Heal and watch you foes die in rage. I cannot count the amount of times I've killed someone with the ole bait heal. In late game the extra 10% max heal you get from Summoner's Resolve can heal you and your team for a lot since you're very very tanky.
But only use this ability for three occasions.
1. Baiting enemies into your turrets/rockets
2. Healing a teammate that is going to die.
3. Healing your entire team mid-fight to help establish dominance.

The essentials of Dingus in the game phases.

Early Game: Harass with your Hextech Micro-Rockets while getting tanky items as such as Doran's Ringand a Catalyst of the Protector. Be aware of the enemy jungler and always be in position to run to your turrets.

Mid Game: If you see your opponent gone from lane and you know where the enemy team is, it is the time to push in your lane to damage and eventually take the tower. Help your team out in occasional ganks in the side lanes and move to other lanes if you already destroyed the mid lane tower. Always be on the move after your turret is gone and help push in the other side lanes.

Late Game: Group up with your team after you have destroyed all of the outside turrets and gank the enemy team. When in a team fight, do not be afraid to get in the middle of it and drop H-28G Evolution Turret in the thick of battle. Place your turrets at exit points or in the dead center of battle and activate your ult. Heal when you need to and always keep pushing. Since you are Heimerdinger you are always one of the top targets since people perceive you to be a slow and squishy caster. Use this to your advantage and kite your enemies into brushes or around your H-28 Evolution Turret.

Team fights: Before you engage in a team fight try to actively harass your enemies with long range Hextech Micro-Rockets and Ch-1 Concussion Grenade. When you see them charge you or your team charges them, you must use your Ch-1 Concussion Grenade as your initiating spell and drop your H-28G Evolution Turret. Spam Hextech Micro-Rockets in the middle of the fight and actively look for their carries and use your Ch-1 Concussion Grenade on them. Position is key for your rockets and turret placement. A good turret placement can slow an entire team down in their tracks and end up doing loads of splash damage. Be mindful of who your using your rockets on because you always want to Hextech Micro-Rockets the supports and other non-tanky heroes in mid-fight.

Brushes: If you see a wondering enemy about to run threw your brush, wait till the last second to place your H-28G Evolution Turret down and activate UPGRADE!!! if you have it. I like to call this the Candy Shop because people always wander in brushes and all you have to do is wait. Also, if you are running away from one or more enemies do not be afraid to turn around in a brush and ambush them with a Candy Shop. With a well placed Ch-1 Concussion Grenade, you will be surprised how much damage you do to them.

The Roadblock: If you see your team chasing down other champions and you happen to be coming up behind them, lay down the Roadblock. Place your H-28G Evolution Turret in the direction their running or their only exists and stun them with your Ch-1 Concussion Grenade. If they try to push through the Roadblock activate UPGRADE!!! and stop them in their tracks.

Neutrals: If you are doing [u][color=#ff0000]Dragon[/color][/u] or [u][color=#008000]Baron Nashor[/color][/u], always keep your H-28G Evolution Turret in the entrance way of the pocket. This way you can still attack the neutral and attack enemies who try to come stop you in the river.