The planets of the Origin System are plagued by periodic infestations of the Technocyte menace, which sweeps across entire sectors, replacing the Corpus or Grineer in those areas until they are eliminated once more. When the leader of a planet comes under attack by the Infestation, a certain monster emerges from the shadows to lead the Technocyte hordes as they fight to overwhelm the opposition. A massive, ancient evil, Phorid always appears where the battle is fought the hardest.
Lotus: "One of our spy cells has been lost investigating this abandoned Grineer asteroid base. We need you to locate and eliminate whatever is responsible."
Lotus: "This place is crawling with Infested. Unfortunately, something far more ominous awaits. Make your way deeper into the base."
Lotus: "Your target is an aberration of twisted flesh. Put the thing out of its misery."
Lotus: "Elude its bone-chilling shrieks if you wish to stay alive."
Lotus: "Avoid the creature's spine-strike. These razor-sharp quills will rip your warframe to shreds."
Lotus: "The creature is incredibly agile for a deformed quadruped. Keep moving to avoid being crushed."
Lotus: "Listen to its screams. This will mean you are getting close."
("Revoke the frailties of flesh. Let us in.")
("We are the vessel through which immortality is achieved. Assimilate, [name].")
There are a small number of dialogue lines from the time when Phorid was the boss of Eris that have since been removed from this boss fight.
("Through the coalescence of flesh and universal will, we will exist as one.")
("Tenuous is your human spirit, [name]. Let us be your salvation.")
(mission complete) Lotus: "Infested encounters are beginning to reach nightmare-like proportions. This latest abomination proves that there is no limit to the imagination when dealing with these monsters."