Atropus biome, but dark.
Possible Weather
Bio Rain, Blood Rain, Light Gravity Rain, Gravity Rain, Poison Gas, Dense Poison Gas, Deadly Poison Gas.
Planets that list poison gas as a weather type require poison resistance in order to survive on them. Using a Tinkering Table (which is crafted at a Machining Table), you can craft a Poison Shield augment. EPP Augments can be attached to EPPs by opening your inventory, clicking an augment, and right clicking the EPP you wish to attach it to.
An alternate method of obtaining poison gas immunity is to craft an Armorworks at a Machining Table. You can then craft a Blister Shield to receive poison gas immunity while the shield is highlighted on your hotbar, or craft a set of Blister Armor to receive poison gas immunity at all times while the full set is equipped. Note that if you wield a Blister Shield for poison gas immunity, opening your inventory and moving items around will briefly remove your immunity. This is most likely a glitch.