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The entire life-cycle of the Sea Dragon Leviathan is almost exclusive in the Inactive Lava Zone and Lava Lakes only leaving their natural habitat in order to sustain their food supply by hunting Reaper Leviathans in the shallower waters. Similar to the Lava Lizard, the Sea Dragon is completely resistant to the Thermoblade. The Sea Dragon Leviathan will get stuck inside the walls of the map, but still be able to attack the player. When the Sea Dragon Leviathan is exposed to damage, it will flinch and commonly, if the player is close, it will swat them away dealing large amounts of damage to the Player if they aren't in any Vehicles. A sustained barrage of small fireballs, known as the Fire Breath attack, can deal lots of damage in a short time to the Prawn, it'll often swat the vehicle soon after and do this again if you're still in the vicinity. The Sea Dragon Leviathan can deal massive damage to a Prawn Suit very quickly the swat attack does 11% damage to the suit, the Sea Dragon Leviathan also has the ability to grab the vehicle in its mouth and deal 10-20% damage before releasing it it often swats immediately after. The Sea Dragon Leviathan will attack the Cyclops by slamming it with its arms with considerable force, often leaving the Cyclops upside down or on its side. The Sea Dragon Leviathan is also capable of firing a barrage of small "fireballs" covering a wide area.
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Occasionally, the Sea Dragon Leviathan will open its mouth wide and fire a molten rock at its target as a projectile attack. If the Sea Dragon Leviathan attacks the player with its mouth, it will swallow the player, killing them instantly even if the player has the Reinforced Dive Suit equipped. It will attack the player with its arms if they are on either side of its front body by swatting them away and dealing 40 damage to the player. Just being in close proximity to the Sea Dragon Leviathan will cause the player or Prawn Suit to be jostled due to the water it displaces. The Sea Dragon Leviathan uses its arms and tentacles to swim in the water at great speed according to the "Damaged Anchor Cable" entry from the Disease Research Facility, it is capable of exerting over 300 tons (600,000 pounds) of force by ramming.
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Its rear-side consists of seven tentacles, also lined with orange spots and ending with small tentacular clubs, the largest tentacle being surrounded by the six smaller ones. A large sail sits on the creature's back, just below the shoulders. It has two long forearms ending with webbed, four digited hands each digit ends with a claw that is approximately equal in size to the player's entire body. Along the side of its body runs two long trails of small hollows that emit orange bioluminescent glows.
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It also has a second set of larger fin-like protrusions beneath its lower jaw. The tip of the snout features two short, green protrusions with orange glowing tips. The mouth contains a pink tongue and thirty-two large teeth, visible even when the mouth is closed. The head of the Sea Dragon is stout and reptilian, possessing two pairs of glowing orange eyes with white pupils, a crack-like pattern spreads from the pupils to the rest of the eye. Many of its body parts are adorned or spotted with orange bioluminescent glows, and many small spines line its lower jaw and arms. It has protective plates on the underside of its body that start at the neck and run down to where the tentacles begin. The body is mostly dark green in color, along with purple accents on its webbed limbs and head. The Sea Dragon Leviathan's body mostly resembles the Sea Emperor Leviathan, albeit much smaller and slimmer in design.
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