I've already been enjoying defending as Heimerdinger in Dominion and hes just a boss at defending especially when you have 3 guys chasing you blind around a capture point while you barrage them with your skills.

Passive Techmaturgical Repair Bots: HP regen aura for everyone huehuehue

H-28G Evolution Turret: Heim's Prime defensive weapons that don't look that intimidating but deal a lot of sustained dmg and now the armor/mr reduction will really take a toll on the attackers now that you can survive for a long time.

Hextech Micro-Rockets: At the start not really too much of a threat besides minor harassment but is an amazing disrupting tool by late game they will be pretty scary and you can use them from a safe distance away.

Ch-1 Concussion Grenade: Your auto attack killer while doing respectable dmg can blind and stun on direct impact using this while defending is just laughable because they will miss you and at max rank the blind is for 3 secs which is more than enough time for the turrets and the rockets to either scare or kill a champion trying to take the point or kill you.

UPGRADE!!!: Passive CDR along with the great ability to heal your turrets and slow on hit to kite enemy champs around the point and keep them from touching you.

Reds: Magic pen
Yellow: Armor per lvl
Blues: Magic resistance per lvl
Quints: actually depends what you want I don't really have armor per lvl quints but I think they would work best but right now I have 1 magic pen and 2 CDR quints

Although it is a tank build you need the CDR for your summoners and abilities to spam Promote, Exhaust, your abilities to make sure the enemies suffer for attempting to take the point but man those grenades on point blank range stun and blind way to useful 3 seconds if 3 melee ad come to your point expecting you to die easy they will be very disappointed when you outlast them for the triple kill or you can make some flee for their lives.

The only thing that will change are the boots and I'll give the reason for each item and how it is essential

Tear of the Goddess : must be built with either armor or boots at first and you will use the time at the start to get more free mana pool and will be built into Archangel's Staff after the boots are finished.

For boots it is either Ninja Tabi or Mercury's Treads depending on the enemy team.

Frozen Heart will make all ad less scary as well as giving you AP from the Archangel's passive and very useful CDR.

Warmog's Armor : built mainly because Heim doesn't have a big health pool and it will also give you plenty of hp regen.

Force of Nature : Gives you magic resistance to survive through magic bursts mainly built to counter the very scary Akali or Jax on the other team since they will look to dive you often. Aside from that FON works well with Warmog's giving lots of hp regen and more movement speed to kite with. If for some strange reason the other team has pitiful magic dmg you can grab Thornmail instead.

Zhonya's Hourglass : c'mon man this is just ridiculous you mean you can become invincible for 2 secs with this active! Amazing item at any point and you can chill while the turrets fire on the other team and then come out and throw a blind. On top of all that it gives you a lot of armor and AP. At this point Heim is just a living cheat code when it comes to defense it should take at least 3 people to take you down at a capture point.

Promote: used to push a lane heavily or gain gold while defending at the point and with the reduction from the Mastery Tree it should be available pretty often.

Exhaust: Basically an additional blind or you can use it in a lot of other situations to save teammates or make sure the enemy champ doesn't get away. Great because its just another kiting/blinding spell to use when defending

Garrison: Really useful but really doesn't matter when they counter it with a Garrison themselves and you rarely use the offensive version of the spell.

Flash: You won't normally need it that often because you normally won't have the movement speed to escape even after you flash.

Ghost: Good for kiting but if the enemy has a slow its really not to useful since Heim is normally slow already.

9/29/2011: Made the format look a lot better

Tankerdinger is used to stall the enemy for a long time or successfully depend a capture point. By the end of the build believe it or not if you are skilled you can 1v1 a lot of champs point blank just throw down your turrets grenade for blind/stun and rocket dps. The turrets will eventually take down the champ because you just don't want to die even with the enemy having armor pen you have a 20% attack speed reduction. Lastly your not going be just a tank your dmg is still threatening which is simply just great since they can't just avoid your dmg.