Heimerdinger is all about positioning turrets and pushing the enemy champion back, killing him/her and dominating your lane

You can often hear that Heimerdinger is op. This is because of his turrets. They may be squishy and take approximately 21 seconds to generate one, but once all 3 of your turrets are down you can easily dominate your lane and turn ganks in your favor. I once had all three turrets down and the whole enemy team tried ganking me because i was so op. They had a Darius, Le Blanc, Morgana, Jinx and Warwick. They all grouped up behind me and dived into my turrets i then stunned them with the grenade and used my upgrade with a turret. The upgraded turret doesn't count as one of the three turrets you already have down. After placing the upgraded turret i bombarded them with only my regular rockets and got a pentakill within seconds. 3 minutes later we won the game.

Essentially this is where all your burst damage and is what you will usually be using upgrade with. You fire four rockets that converge on your cursor and fan out after it. this ability scales amazingly with ap. Using upgrade will let you fire 4 waves of rockets with increased damage, with this build that damage will amass up to about 1300 damage. this is enough damage to kill and adc who is at full health. you will max this ability second

You launch a grenade at a target location those directly in the blast are stunned and those around it are slowed. you should use this ability when you want to get a hit with rockets but the enemy champion is moving too much or when the have dived your turret so that they cant do any damage but are continuously taking damage.you should max this ability last.

This is the ability that makes Heimerdinger tick. You can upgrade one of your abilties for it to do a bonus effect.
Turrets: place a big more op turret that lasts for 8 seconds and does massive damage
Rockets: shoot 4 waves of rockets at the target location that deal enhanced damage
Grenade: Shoot a grenade that bonces 2 times in a line with a wider aoe
max this ability whenever you can