How to complete Marathon Tox Clear events

Marathon player using Hazard Override Card on red laptop for Tox Clear — (Image credit: Bungie)

The Marathon Tox Clear event is an optional challenge that allows you to get some nice loot either by braving a room of toxic gas or by finding a way to deactivate it. The problem is that the gas in Marathon is so dangerous that it's not worth trying to loot the room's contents and the necessary key is quite rare anyway. Even so, I've laid out everything you need to know about Tox Clear rooms in Marathon and how to temporarily disable to gas.

Marathon Tox Clear walkthrough

Marathon Hazard Override Card on bench — (Image credit: Bungie)

If you want to deactivate the gas in a Marathon Tox Clear room, you need to have a Hazard Override Card, a type of Enhanced Key that you can find while looting. In my experience, Hazard Override Cards are quite rare in Marathon, but you should eventually find one just from looting and rummaging through random containers, including dead players. Like other keys, you can exfil with a Hazard Override Card and store it in your vault to use on a later run too.

Marathon Red laptop and Tox Clear room — (Image credit: Bungie)

If you have a key, you then need to find a red laptop near the Tox Clear room itself, so explore the surrounding area for it. The laptop's screen also has a symbol that matches the one on the inactive gas extraction devices in the room. You can then use the key on the laptop to temporarily clear the room of toxic gas and loot the trunks within. The room refills with gas after about 30 seconds, so you need to be quick to grab everything unharmed.

Of course, you don’t need to vent the gas as you can open the door to the Tox Clear room and loot all the trunks inside anyway. You'll obviously be horrifically poisoned and mechanically debilitated, making all your healing items worse for quite some time – the damage-over-time Toxin effect may even be enough to kill you – so it's up to you whether you think it you can handle it.

If you've got Mechanic's Kit consumables, you can use them to remove Toxin effects and bolster your Hardware stat, which will make looting in the gas a bit less dangerous. Make sure you've also got plenty of healing items, preferably including a Triage Med-Drone (he's one of the best Marathon Runner Shells to have on your team!), and don't wait until the last minute to use them!

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Will Sawyer is a Guides Editor at GamesRadar+ with over five years of experience in writing online guides, news, and features, and has a BA (Hons) in Journalism. Starting as a freelancer, Will contributed to startmenu and Game Rant before joining the GamesRadar+ team in August 2021. Since then, he has written hundreds of guides about a huge range of games, with shooters and action games being his areas of expertise. Outside of writing about games, Will hops between multiplayer shooters with friends, such as Darktide and Helldivers 2, and delves into whatever has been on his backlog for far too long. He also tries to get through his never-ending Warhammer pile of shame of grey Tyranids, Aeldari, and Chaos Space Marines.