The Plains of Eidolon is an expansive, open Landscape connected to Cetus, an Ostron settlement located on Earth. In the shadow of the Orokin Tower of the Unum lies an ancient battlefield, where an enormous Sentient was defeated during the Old War. The Grineer have set up numerous outposts and bases to study and mine the ruins in the area, observing and patrolling the plains for any threat to their operations.
This open zone was introduced October 12th, 2017 in Update 22.0.
The Plains of Eidolon has an area of about 5 square kilometers (2.25km x 2.25km), featuring various fields, hills, caves, and bodies of water in a mostly temperate climate. Unlike other mission nodes, the Plains of Eidolon is not procedurally generated using Tiles, but is instead a massive static map with unique features.
The Plains are accessible through two different mission nodes on the Star Chart, both nodes are on Earth. The first is the central hub of the Plains - Cetus, Earth - where the player will spawn on the shores outside of town. The second mission node will spawn the player directly in front of the gate that connects Cetus to the Plains. Both nodes will be unlocked directly after completing Vor's Prize and are not Mastery Rank locked.
Each server instance of Cetus can hold up to 50 players within the town, however players can only exit onto the plains in the standard 2-4 man squads or Solo. Each map is considered its own separate mission instance, and will not be shared between squads.
Entering into the Plains from either Cetus or directly from the Star Chart will create a new mission instance of the Plains, with procedural generation applying to objects like resource spawn locations and mineral veins, as well as assigning a random Challenge.
Progress on the plains is saved under the following conditions:
- Upon returning to Cetus through the gates at any point, with the mission concluding and all progress saved.
- On returning to the player's Orbiter via the escape menu.
- All progress is automatically saved on completing Bounties or Incursions.
- Fishing, Mining, or using consumables results in a specific save of that content (fish caught, minerals extracted, consumables used).
Day & Night Cycle
Unlike with the Earth tileset's traditional day and night cycle which is set upon entering a mission, the Plains of Eidolon feature a real-time cycle which sees the map seamlessly transition from light to darkness. Daytime in the Plains lasts for 100 minutes, while nighttime lasts only 50 minutes. All players will experience the same time of day at any particular time in the Plains of Eidolon.
The time of day determines the type of enemies as well as the type of fish that players can encounter on the fields, and consequently affect the map's difficulty level. While the day cycle is more directed towards new players, the night cycle is reserved for more experienced players, with the more difficult enemies of the Sentient faction.
Occasionally, the Plains of Eidolon can experience rainy weather, ranging from soft drizzles to thunderstorms. During rainy periods, Grineer enemies in the Plains will experience reduced visibility, and Fish have a higher chance of spawning on bodies of water.
Other weather effects present in the Plains include varying strengths of wind, which can act on objects like trees, grass, and even Syandanas.
- Main article: Fishing
The Plains of Eidolon feature large bodies of water, which house a wide variety of aquatic life. Players can engage in spearfishing to catch various fish and crustaceans, which can then be used as resources to craft various Ostron items or gifted to Fisher Hai-Luk to increase standing with the Ostron faction.
- Main article: Mining
Another means of getting resources in the plains is through mining; players can find mineral veins, visible as bright glowing marks, scattered throughout the landscape, which can then be mined with a dedicated cutting tool. Ores and Gems are used in a variety of crafting recipes, and uncut gems can also be traded in to Old Man Suumbaat to increase standing with the Ostron faction.
The Plains currently features two indigenous species of wildlife that roam around the field, the Kuaka, a small rodent-like creature and the Condroc, a large bird-of-prey. These species can be hunted and killed to drop resources unique to said animals.
- Main article: Bounties
Bounties are randomly generated quests in which the player completes a series of short objectives from Konzu. Upon completion of a set of missions, the player will be randomly receive a reward from the reward pool.
- Main article: Incursions
Incursions are random optional mission objectives that can occasionally pop up in the Plains, that give various rewards upon completion. Unlike Bounties, Incursions can only occur during daylight hours.
The Plains of Eidolon have several caves which players can enter, which can contain items of interest such as minerals or Codex objects. Many of these caves are small spaces that can have multiple openings that players can go through to access the cave.
Certain caves in the Plains however have closed Grineer doors inside of them, which act as the only entrance to the cave proper. The majority of these sealed-off caves can only be accessed upon the game creating an Incursion or a Bounty objective that takes place within said caves, at which point the door lights become green, indicating they can open. Unlike the smaller caves, these caves open up into massive, expansive caverns, and even lead into outdoor locations outside of the Plains' boundaries. Of these large caves, only the cave located by the geyser pond near Cetus can be accessed by players without the need to activate an Incursion or Bounty.
Caves that have been discovered by players will be permanently marked on the minimap by a white jagged triangular symbol.
The Grineer, comprised of the special Tusk Corps, are the primary enemy faction in Plains of Eidolon during the daytime and can be found in either small patrol groups roaming the plains, or stationed at one of several outposts and firebases they have set up in the area. The Grineer firebases are heavily fortified with various defenses, including Ramparts and automated heavy defense turrets. For added firepower, these firebases are also capable of using mortars that lob high explosive shells at long range towards their targets. These Grineer units are unique as Eximus variants can posses the Venomous and Shock versions, normally only used by the Infested and Corpus respectively. They also use special Heat and Cold grenades not used by other Grineer units in the system.
The Grineer units can spawn at the Plains in different ways, either via Firbolg dropships or descending from orbital drop pods. They can also be deployed from Bolkor gunships, which are armed with rotary cannons for close air support. All the aircraft on the Plains are vulnerable to attacks and can be destroyed before they deploy the units they transport. If a sufficiently large patrol is engaged in combat, the Grineer units will deploy Tusk Seeker Drones that will signal for reinforcements, which then will proceed to spawn via the aforementioned options. The drones will continue to call in additional enemies unless they are destroyed.
The Grineer can also field airborne units such as Dargyn skiffs and Ogma bombers to patrol the plains and attack from the air. Once these air units are defeated, the ejected Dargyn Pilot may drop to the ground. The Dargyns can also be found parked near Grineer encampments, and can be hijacked if the pilots are eliminated or beaten to the vehicles.
Supporting the Tusk units are the Ghouls, consisting of heavily malformed Grineer that lie in wait beneath the ground for an ambush. When confronted, they burst out of the ground and unleash their animalistic instincts, savagely attacking anyone who dares trespass their territory. When killed, their blood releases Cold Toxin cloud that paralyzes and renders the enemy ever more vulnerable to Ghoul assaults.
During nighttime, the Grineer will retreat to the safety of their outposts, reducing the number of Grineer that can be encountered on the field during that period, though in turn raising the difficulty of a nocturnal assault on a base. Eidolon Lures will be deployed around the encampments, as the Grineer are hostile towards the Sentient and will attack if they encounter them, even the massive Teralysts.
During the Old War, a major battle against the Sentients took place on the Plains. The Sentient was defeated, scattering its fragments all over the area, resulting in the existence of the ghostly Spectral Sentients, also known as Eidolons. These are absent during the day cycle and show up only at night, increasing the difficulty of the Plains.
The main Sentient threat on the Plains during the nighttime are the Eidolon Teralysts, gigantic Sentient units equipped with powerful weapons and formidable defenses. Taking down a Teralyst is no small feat, requiring concentrated firepower from Operators and their Warframes. A full squad is recommended for this fight, though it is also possible - though extremely difficult - to defeat a Teralyst solo. Also roaming the plains at night are the smaller Eidolon Vomvalysts. Should a Vomvalyst be reduced to zero health it will shed its outer armor and turn into a glowing spectral form, complete with a fresh pool of health impervious to weapons fire but vulnerable to an Operator's Void powers. Eidolon Lures will absorb Vomvalyst sentients after the outer shell is destroyed, relieving the requirement of an Operator to destroy them.
Additionally, in the middle of the Gara Toht Lake there is an Ostron altar dedicated to the Eidolons. When players offer their Brilliant or Radiant Eidolon Shards to this altar, they can summon the even more powerful Eidolon Gantulyst and Eidolon Hydrolyst.
Several Grineer outposts in the Plains house Ammo Dispenser units, visible as green containers with a white holographic display at the front and a floating green holographic bundle of ammunition on top. Interacting with these dispensers (default) will make them drop ammunition for all weapon types, which can then be collected by players. The dispensers have a 3:20 minute cooldown time, during which the dispenser cannot be used until its cooldown has elapsed. During this phase, the white display at the front will show the time remaining on the cooldown, and the holographic ammo bundle will change color from green to red.
Grineer outposts and bases in the area can have Armored Vaults on them, seen as large orange and green tracked carriages with control consoles on them. These Armored Vaults can be opened up to by interacting with the control console, giving a small amount of resources, and sometimes they will have a single Storage Container inside that can be broken for more drops. Armored Vaults are also used as the objective in Resource Theft Incursions.
Some Grineer outposts on the Plains have green communication towers with control consoles on them, which nearby Grineer can activate to call in reinforcements. Players can hack these towers to deactivate them, which will also deactivate any hostile turrets within the outpost. These towers could also occasionally be heard broadcasting Grineer propaganda from Councillor Vay Hek, as a prelude to Operation: Plague Star.
The Grineer encampment near the Hillside Ruin (marked as #3 on the map) in the Southeastern part of the Plains is host to an archaeological excavation setup that can be interacted with. Inside the circular command tent, a holographic map of the immediate area can be found. Activating the switch next to the map will highlight one of three possible locations with a glowing dot on the map, and will deploy an automated mining explosive (similar to a Dreg) from the tent to that location. When it reaches its target, the explosive drone will detonate, revealing fossilized Sentient wreckage and some random assorted resources or Credits.
Note that the explosive drone can be destroyed while it is docked inside the tent or as it travels towards its destination, and the system will become unusable if all the available drones are destroyed.
At night, bodies of water on the Plains will become energized with Sentient energy, which will inflict a Magnetic proc on any unit that touches it, temporarily reducing maximum shields and removing 100 Energy.
A small lake near the Twin Horns (west of the entrance to Cetus) has a small geyser at the center, which blows a powerful jet of steam upwards when units step on it, launching them upwards.
Thousand-Year Fish Statuettes
- Main article: Thousand-Year Fish
Thousand Year Fish statuettes are small, glass statues scattered throughout hidden locations in the Plains. These can be scanned into the Codex to give in-depth lore about Cetus and the Plains.
- The Arsenal can be accessed from anywhere in Cetus via the Main Menu, then selecting Equipment => Arsenal. This allows switching of loadouts in Cetus without needing to return to the Orbiter.
- The accessibility of the closed large Grineer caves on the Plains are determined upon the creation of a Bounty or Incursion created within a particular map instance. Caves made accessible by Bounties will remain open even if the player fails any bounty phase before reaching them, however exiting the Plains will close said caves.
- In some of the Lakes scattered around the Plains, most notably the one with a small, Grineer populated island in the middle of it, a player's warframe can become completely submerged in the water, and will be standing on the bottom of the lake. The camera, however, will be unable to pass through the surface of the water. This seems to only happen near the center of the lake, around the edges the correct events occur. Bullet jumping and other forms of movement still allow you to resurface.
- The stream on the northwest corner of the Plains may be permanently magnetized, regardless of time of day.