Gas damage is a secondary damage type in Warframe, meaning that it is achieved by mixing two primary damage types. To add Gas damage to any weapon, you need to use a mix of mods that do Heat and Toxin damage.
Gas damage will cause a status effect called Gas Cloud. The cloud has a 3-meter radius and will cause tick damage to any enemies standing in it. Subsequent procs of Gas damage will increase the radium, maxing out at 6 meters after 10 stacks. Tick damage does not scale with elemental mods. At the moment, Gas damage is not considered to be in a great place by most of the player base.
To add Gas damage to any weapon, you need to mod it with the two elemental damage types Heat and Toxin. Some weapons in the game also do innate Gas damage and are a great way to quickly wrap up any challenges, such a Nightwave daily or weekly missions.
The following weapons all do innate Gas damage:
- Telos Boltor
- Telos Akbolto
If you do not have any of these weapons, it is a simple matter to add Gas damage to any weapon. Simple go into your Arsenal, then the Upgrade portion for any equipped weapon, and add a Heat and Toxin mod. You need to make sure that there are no other elemental damage mods that will interfere with the damage type, so be sure to check the stats on the left-hand side of the screen and make any necessary changes in mod order to ensure the weapon does Gas damage.
A straightforward weapon to add Gas damage to is the Ignis, and Ignis Wraith variant. These weapons do innate Heat damage, so simply adding a Toxin mod will change the damage type to Gas instead.