Overall Look

Gaslight Joker (GlJ) is a powerful tank with excellent line sustain and good controlling ability.
This guide is about disrupting enemy team while soaking a lot of damage. The main thought here is to give a lot of HP and enormous slow.
Stolen Powers
[[Shazam's Invulnerability]] - helps keep yourself a life for a timed kill or escape. Prefer better than doomsdays because it gives health that is essential for GlJ skills
[[Zatanna's Psychic Assault]] - perfect for early kills.
Alternative:
[[Superman's Super Strength]] - great initiation
[[Gaslight Batman's Surveillance Camera]] - great support item to keep your carry or yourself alive
[[Poison Ivy's Healing Wave]] - great healing power if you use it at starting point of a teamfight.
Amplifiers/mods
Olympus Gambit (4) - Altered Olympus Gambit - useful health and credits earlygame
Atlantean Royal Seal (4) - Emowered Atlantean Royal Seal - additional slow from skills
[[Ra's al Ghul's Robe (2)]] - Empowered Ra's al Ghul's Robe - second life, second chance
Amplifiers - anything that gives health/armor based on level.
Gameplay/Item build
Earlygame:
Purchase
Olympus Gambit (2). Grab the camera from base. GlJ is not so good on mid so your choice is either to solo top or go bottom with a marksmen/blaster. Place the camera on stealth pad, wait for 100 credits and port back for
Modular Health Vial (2). Farm safely on line till level 2. You will have Fetid Cleaver and Ham snack - time to start a poke. Throw the ham at enemy back, close in immediately and give him a cleaver in the face then fall back. Once opponent will have less than 30 percent health - continue the combo with Psychic Assault and finish the business. remember that if possible you should leave a kill to your carry, do not be greedy.
GlJ is perfect on line cause he constantly receives HP from Q and passive - that is why i consider him very strong topliner.
Continue with
Modular Health Vial (3) and
The Crime Bible (2)
Midgame:
The key here is to push, push and push. You already have some health - but obviously lack armor. Combination of [[Ra's al Ghul's Robe (2)]] followed by
Phantom Stranger's Necklace (2) will gave you ot only 95 Atack armor and 75 Power armor once maxed - but also second life. AND you will not loose necklace stacks.
After making sure you are tanky enough - time to get serious. Go for [[Lobo's Chain (4)]]. Health + damage for your basic attacks + SLOW. As for the skills - remember, DO NOT LEVEL YOUR ULT more than once - you do not need damage from it, its first function for you is AOE slow. In team fights - start with ham toss to break enemy position than activate ult and immediately close with your enemy targeting assassins/marksmen/blasters. Hit them with a cleaver followed by AA and stick to them - slow from ult + lobos chain will almost always lead to a kill or two for your team.
Lategame:
Going for the finish now. Sell
Modular Health Vial (3) and build
Atlantean Royal Seal (4) - even more slow and some more power for your Q and W. Finish
Phantom Stranger's Necklace (3) and
Olympus Gambit (4)
You should be almost unkillable and be a great disruptor for enemy team with 3 slows.
Alternative items:
Suit Of Sorrows (4) / [[Mirror Master's Prism (4)]]- big amount of Attack/Power armor and reflect
Spear Of Destiny (2) - if you need a bit more basic attack damage, scales with Max HP.
Fragment Of Mogo (3) - Attack armor, health and great active ability for teamfights.
Kryptonian War Armor (4) - Power armor, healing bonus synergizes with passive and Q.
Each time you do not have money for item you want - purchase [[Hawkman's Harness (1)]], then maximize and sell it once needed.
Resulting item bonuses:
Health: +1275
Health regen: +70 health per 10 seconds.
Attack armor: 120
Power armor: 100
Cooldown reduction: 10%
Power damage: +50
Atack dfamage: +30
Hope this guide will be useful. Envoy this great game!