Weak Point: Head
From Body: Lagiacrus Hide, Lagiacrus Scale, Lagiacrus Claw, Shell Shocker, (High Rank Only) Lagiacrus Hide+, Lagiacrus Scale+, Lagiacrus Claw+, Shell Shocker+
From Tail: Lagiacrus Tail, Lagiacrus Scale, Lagiacrus Plate, (High Rank Only) Lagiacrus Scale+, Lagiacrus Plate, Lagiacrus Scale+, Lagia Sapphire
Quest Reward: Lagiacrus Hide, Monster Bone L, Lagiacrus Plate, Shell Shocker, (High Rank Only) Lagiacrus Hide+, Lagia Sapphire, Shell Shocker
Special Reward: (Destroy Horn) Lagiacrus Horn, Lagiacrus Scale, Lagiacrus Plate, (High Rank Only) Lagiacrus Horn+, Lagiacrus Scale+, (Destroy Chest) Lagiacrus Hide, Lagiacrus Scale, (High Rank Only) Lagiacrus Scale+, Lagiacrus Hide+, (Destroy Spine) Lagiacrus Scale, Shell Shocker, (High Rank Only) Lagiacrus Scale+, Shell Shocker+, (Destroy Claws) Lagiacrus Scale, Lagiacrus Claw, Wyvern Claw, (High Rank Only) Lagiacrus Scale+, Lagiacrus Claw+
Glitter Drop: Lagiacrus Plate, Lagiacrus Scale, Wyvern Tear
You may recognize this guy from the game's box, and truth be told he's not as bad as you might think. He certainly looks imposing, what with with his massive size and such, but in actuality his size is more of a liability then anything else. This is because the attacks that Lagiacrus depends on the most will come from it's mouth or tail. The rest of his length is just there, leaving you with any number of points on its body to attack almost without consequence. Well, not entirely without consequence. Lagiacrus does have a spin attack that can get you while you're attacking its flanks, but even this is pretty easy to avoid.
This is something you'll notice will most of its attacks. They can be devastating if they actually connect, but getting around them is pretty simple. It will charge, but always in a straight line, meaning that if you stick to its sides as suggested, it will shoot right past you. It will shoot balls of electricity at you, but again, in a straight line. Just stay out of its line of fire and you should be fine.
The biggest thing to worry about with Lagiacrus is it's electrical attacks. We've already mentioned that it can shoot electricity at you, but that attack is pretty negligible. That said, it can also perform a wide area attack that will electrify the area around its body. This can sneak up on you, and if you're underwater your clumsier movements can make it difficult to avoid. Keep an eye on Lagiacrus' back. As Lagiacrus' power level grows, the spikes on its back will glow blue. When they reach their brightest, keep your distance. Aside from this the most difficult thing about Lagiacrus is that a ninety percent of fight is underwater which really hampers your movements. It's easy to make mistakes, so bring a bunch of healing items along just in case.
Weak Point: None Discernible
Elemental Weakness: Water
From Body: Uroktor Scale, Dragonfell Berry, Monster Bone M
You will find Uroktor popping up and down out the ground in volcanic terrain. Conk one on its head to get its attention. Fighting these is fairly straightforward, but do be careful. If they pop back into the ground they can stab up at you and they can also spit flame at you, setting you on fire.
Weak Point: None Discernible
Elemental Weakness: None Discernible
The Uragaan looks similar to Barroth but in truth is a much more potent foe. Its mobility combined with its general brute strength can make it a frustrating foe. When fighting Uragaan, you can generally count on being on the defensive. You'll spend most of your time dodging, and then working in your own counterattacks when the opportunity arises. The safest place to attack is generally behind its legs, in what you could say is its crotch. Even this comes with risks, though. Uragaan can blast out clouds of sleep gas or fire that will either damage or disable you.
The biggest things to watch for are generally very visible. When it curls into a ball and begins to roll, make sure you are out of the way. Where Barroth only charged in a straight line, Uragaan can change course. Touching any part of its body while it rolls will damage you. If you see it begin to pound its head on the ground stay clear of its front quarters. While performing this attack Uragaan stands in one spot, which can serve as a good time to get in your own hits, but if you are even close to the shockwaves emitted by the head slams, you'll take damage or be temporarily immobilized. Lastly, keep an eye on Uragaan's tail. Its tail swipe is nothing altogether too special, but it does have a wider than normal range which can catch you if you're too close.