Kuva Siphon

Kuva Siphons are Grineer harvesting machines that can occasionally be found in any Grineer non-endless mission above level 30 (Sortie and Syndicate missions like Survival or Defense included) and on infested grineer tileset (It is not known if that's bug or not). After completing of The War Within quest they can be destroyed to obtain Kuva.

By their own, Kuva Siphons are harmless and cannot be directly damaged by the player's weapons or abilities, however they are accompanied by Grineer reinforcements to defend it, which also includes Kuva Guardians and Kuva Jesters.

Harvesting Kuva
Kuva can be obtained from Kuva Siphons through the following process:
 * 1) Find the machine, which will be highlighted by an Assassination marker when players near its position, along with the rooms near it gaining a reddish-pink hue. Approaching it will trigger the siphoning process, indicated by either the Lotus or a Grineer Queen making transmissions about it.
 * 2) Wait for the machine to start making its distinctive noise. One of its four Braids will be raised at this time. The Siphon's raised Braid will point towards the incoming cloud, making it easier to locate.
 * 3) Locate the red-black cloud of Kuva approaching the machine from somewhere in the room, which will make a distinctive sound as it approaches. Around this time, Kuva Guardians and Jesters, as well as regular Grineer enemies will move in to secure the machine.
 * 4) Switch to Operator form and Void Dash through the cloud, intercepting it. This will destroy the active Braid.
 * 5) Repeat this four times, once for each of the Siphon's Braids. Once all the Braids are destroyed, the Kuva Siphon will explode and award every member of the Cell around 550-700 Kuva.

If the Siphon manages to absorb 8 clouds of Kuva before it is destroyed, it will disappear, and every member of the Cell will be awarded up to 225 Kuva. Any remaining Guardians will disappear along with the Siphon whether it is destroyed or successfully escapes, but Jesters will stay in mission.

Tips

 * When in a group, killing the Guardians as quickly as possible is imperative to prevent them from interfering in the player's Kuva collection. When playing solo however, it might be best to focus on collecting the Kuva rather than killing the Guardians.
 * Bring in crowd control frames to ensure that Operators will be able to survive long enough, since high level Grineer are capable of killing them quickly with their weapons.
 * This will help with the inflow of regular enemies, but Guardians are somewhat resistant to abilities, meaning that killing them is still ideal.
 * Another alternative is to bring Warframes with high armor and/or health pools to allow them to survive frequent Operator deaths.
 * A range-duration specialized Ivara is capable of harvesting Kuva Siphons solo by using her Quiver's Sleep Arrow for crowd control, and Cloak Arrow to hide Ivara and the Operator from sight, allowing them to more safely gather the Kuva clouds on approach and, if desired, safely engage Kuva Guardians at the same time.
 * Clouds of Kuva that are out of line of sight can be located with Codex or Synthesis Scanners.
 * It is possible to invite players to a mission upon discovering a Kuva Siphon in order to more easily farm the Kuva Siphon, provided that the mission's objectives have not been accomplished.

Bugs

 * Ash's Blade Storm will target Kuva Clouds and Kuva Siphons although dealing damage to neither, as such it is recommended to not bladestorm anywhere in the vicinity of Kuva Siphons as you might get stuck for the entire duration of the bladestorm.
 * Similarly Sleep Arrow can open Siphon to finishers, though they will deal no damage.
 * Kuva Siphons might randomly stop spawning dark clouds, preventing Kuva gathering.
 * Kuva Siphon can appear on Infested Grineer tileset.