This is a slow build. It will take you a while to build up to dominate. Before your Seraph's Embrace finishes at 750 bonus mana, you will be pretty squishy. Banner of Command combined with Rabadon's will give your turrets insane damage. 3-shot champs in a team fight, even after you're dead! So make sure to always use your ult for the Apex Turret, not the other options.

The wealth mastery gets you boots and a faerie charm at the start of the game. The extra mana regeneration and the skill-shot dodging will help you harass and stay alive.

Heimerdinger can place 3 turrets right at level 1. Take advantage of this to set up a line of 3 turrets at the entrance to your turret area.

Auto-attack the enemy champion, then run back to your turrets. The minions will aggro on you and follow, into the death beams of your turrets. This keeps the battle close to your turrets and away from the enemy champ.

Use your grenade and rockets to harass. Stun with the grenade and fire rockets. Spread the rockets out by placing your cursor near Heimer to increase the chance to hit. Additional rockets hitting only add 20% more damage, so it's much more worth it to land a hit. If you can keep their mid-laner low health, you don't have to worry about ganks as much, since they can't support the gank. You can stand toe to toe with almost any jungler with your turrets and your barrier.

Once your turrets are level 3, start creeping them forward. Place one inside the range of the previous one. This lets two turrets hit if anything melee is attacking. Keep your turrets further back and safe if the enemy champ is killing them.

Their jungler will gank you. Stay calm. Stay in your nest if you think you can take them. You can bait them into standing and fighting by waiting to pop your barrier until you are very low. Make sure to keep 3 turrets up at all times so that the ganker is punished. I've gotten a kill this way many times, they don't expect you to do so much damage.

Once their tower is down, you are free to roam and help other lanes. Promote siege minions in any lane that is not tended to. Teleport and gank wherever you can. Remember that you can teleport to wards.

Enjoy, and let me know what you think in the comments!