Lagiacrus is a blue Leviathan that mostly dwells in the sea/deep bodies of water and comes onto beaches to sunbathe. It has a hood-like crest on its neck to aid in sunbathing. Lagiacrus is the flagship monster of Monster Hunter 3.
When a Lagiacrus is fully sunbathed, it turns a dry grayish-blue color and its dermal spikes turn a pale red, such as in the picture above. When it returns to the water, Lagiacrus regains a striking deep blue color and its spikes return to their original color of a very light beige.
The dermal spikes on its back glow white when it is using strong thunder attacks, and its mouth gurgles with Thunder when it is enraged.
Known as Sea Wyverns, Lagiacrus are at the top of the aquatic food chain. Feared by sailors as 'The Lords of the Seas', they store enough electricity in their spinal organs to make the oceans surge. Occasionally seen resting on land.
Monster Hunter 3 Ultimate
Leviathans that exist at the top of the aquatic food chain. Feared by sailors as the "Lords of the Seas", Lagiacrus store enough electricity in their spinal organs to make the oceans surge. Occasionally they can be found resting on land as well.
Lagiacrus is the first Leviathan of its kind to be encountered in Monster Hunter 3.
When encountered for the first time offline, in the 1* Village Quest: "Guts- It's What's for Dinner"; Lagiacrus cannot be killed. Its body parts can be broken, and its tail can be carved, but it will only go as far as limping, and cannot be killed until the Urgent Quest in the Village.
When present in Deserted Island , Lagiacrus will, on rare occasion, leave the water and venture no further inland than Area 5.
Even if the Lagiacrus' tail is cut or its parts broken in the "Trial of the Sea Dragon" urgent quest, it will return in "Fell the Lagiacrus" healed and unwounded.
The Lagiacrus is one of the only two monsters in Monster Hunter Tri to have a weapon in every category. The other is Alatreon.