- "That's not a stalk!"
"It's a goddamn Leviathan!"
- —Lt. Anya Stroud and Sgt. Marcus Fenix during the attack on the CNV Sovereign
Assault on Vectes
Three (two big, one small) attacked the towns of New Jacinto and Pelruan resulting in the First Battle of New Jacinto and the Battle of Pelruan. During the battles, the Leviathans released hundreds of polyps at the two towns in attack before the smallest Leviathan was killed by all the ammo of KR-239 being released into its head, the second one being killed by a combined torpedo attack from the Zephyr and the CNV Clement and the last one being killed by the Hammer of Dawn after being lured into a trap by Delta Squad. The first two to die exploded when killed, but the last one beached and it is unclear whether or not it exploded.
A fourth Leviathan attacked, causing the Second Battle of New Jacinto. This one didn't release any polyps although it had at least a few and concentrated on attacking. The Hammer of Dawn failed twice to kill it and then went offline and the gun batteries of New Jacinto and two King Ravens also failed to harm it. The Leviathan made a charge for the oiling jetty which would've detonated tens of thousands of tons of liters of Imulsion which would take out the whole jetty and half of the docks. A depth charge dropped by Yanik Laas and Teodor Marisc from an RIB ruptured its eardrums and forced it to the surface where Marcus Fenix threw a grenade down its throat as the Leviathan was screaming in pain. Realizing it had swallowed something, the Leviathan went into a frenzy and chased Yanki and Teodor. After the Leviathan went under water again, its position was lost until the grenade detonated and killed the creature. A few polyps survived on a chunk of the Leviathan, but Bernie killed them with a Longshot and well-aimed detonations.
Sinking of the Sovereign
- "Marcus, whoah, that's one big, ugly Mother Fucker."
- —Augustus Cole
Later, during a Lambent attack on the Raven's Nest Class ship CNV Sovereign, a huge Lambent Leviathan, twice the size of the ones previously encountered, engaged the ship, catching the COG off guard. It was first encountered when it reached inside one of the Raven platforms, crushing the Raven on it and releasing lots of Polyps. Delta shot the tentacle, causing the Leviathan to retreat. Later on the deck, the Leviathan reared up out of the water and bit down on the deck, causing it to crack open making Delta fall into the engineering deck. After they navigate through engineering, they come up against the Leviathan again as it bites clean through the deck.
- "Uh, puttin' it scientifically? We need to blow his brains out his ass."
- —Augustus Cole remarking on killing the Leviathan
After it retreats once more, Marcus Fenix and the rest of his team made their way to the Silverbacks on the ship and attempted to hold the Leviathan off while Cole's team came up with an idea to get rid of it from on top of Centennial Bridge. Damon Baird came up with a plan to drop Tickers onto the Leviathan and, after fighting their way to a Ticker cage, they kicked the Tickers onto the Leviathan's head and caused the beast to explode. The explosion destroyed the Sovereign and a tentacle strike collapsed the Centennial Bridge where Cole, Baird, Clayton Carmine and Samantha Byrne were. Its remains scattered all over the Hanover coast.
Lambent Leviathans were re-designed as carriers for polyps, and would actively seek out land to deploy their cargo. Lambent Leviathans were also incredibly aggressive, which is believed to be caused by the fact they were in obvious physical pain from Imulsion's ravaging effects on their bodies.