Insania Rex is a powerful Immortal you'll fight about halfway through Daemon X Machina: Titanic Scion. Any good RPG has a dragon fight, and just because you're fighting in futuristic mecha doesn't mean this game is exempt; you'll have to content with powerful melee strikes and a devastating breath weapon during the battle.

While Insania Rex can be a fairly straightforward boss, it's that breath attack that can really throw a wrench into your plans. If you aren't ready for it, that one attack can end a battle that was otherwise going quite well. Here's everything you need to know to slay the dragon.

Best Build For Fighting Insania Rex

Armor

Insania Rex can hit very hard, so midweight or heavyweight armor is a good choice for most slots. A high VP total will help you weather the storm when it comes time to survive the Immortal's breath attack, as will a good Basic Defense. If you can throw some Burn Resistance in via Attachments or ice cream, so much the better.

The only place where you might want to consider going with a lighter armor is your helm slot. Here, you should prioritize Stamina Efficiency; that way, you can more effectively dodge and chase during the fight, and you'll be able to maintain your guard longer against the dragon's breath toward the end of the fight (see below).

Weapons

Insania Rex is vulnerable against both damage types, depending on where you hit it. The beast's underside is susceptible to Physical damage, while its armored back is weak against Laser damage. You're likely to attack from both angles during the fight, so it's a good idea to bring a mix of weapon types.

Since Insania Rex has trouble dealing with targets behind its shoulders, your main weapon should be the best Laser melee attack you can get your hands on; Vermillion Knight is a great choice. For your Physical attacks, choose weapons like knives and handguns that have the Weak Point Exploit trait. These get huge damage bonuses against the prominent weak spot on Insania Rex's chest, to the point where they'll do more damage than gear with higher base damage values.

If you bring a knife, be sure to learn and equip the Caustic Blade skill. Corrosion reduces Insania Rex's overall defense, making the fight that much easier.

Your third slot should be an Energy Shield for the express purpose of defending against the breath weapon. You can technically survive without it if you bring a lot of Repair Sprays, but a shield makes the battle easier by miles.

Finally, choose an all-purpose ranged weapon with a focus on Basic Damage so that you can easily shoot at Insania Rex whenever it's outside of melee range. Focusing on Basic Damage means you don't have to swap depending on which side of the boss you're facing; the idea is to keep the pressure on while you close in, anyway. A Laser Rifle is a good choice for this, as it's one-handed and its damage doesn't diminish with range.

Shoulder Mount And Auxiliary

As with most big Immortals, a homing missile system like Meteorite is a good choice against Insania Rex. Since there are multiple targets along the beast's massive body, you'll always have something to fire at! Alternately, the Devotion repair system can help recover from the fire breath when the time comes.

Your Auxiliary slot is best served by equipping a Cooling System if you've been lucky enough to find one. This lets you easily recover Stamina, which is essential for maintaining your shield in the face of the dragon's breath. If you don't have a Cooling System, a Booster is a fine second choice, as it lets you easily close the distance with Insania Rex when it tries to escape your melee reach.

When you face Insania Rex as part of the story, Iris is in your party by default. Bring her along during Simulator rematches, too — her healing and Corrosion effects are a big help in this fight.

Strategy For Fighting Insania Rex

Start by picking off the smaller Immortals floating around the arena. They'll be a nuisance otherwise, and getting rid of them right away lets you focus on the main boss. Once they're dealt with, hover above Insania Rex's shoulders and repeatedly hit it with Laser melee combos. You may need to dodge occasionally, especially after the boss repositions, but you'll generally be safe if you stay behind their back.

Whenever you stagger Insania Rex, switch to your knife or handgun and perform a grab on the boss's weak point. Both of these small weapons can repeatedly attack in a grab without ending the grapple, letting you strike the weak point for several hundred damage repeatedly before Insania Rex finally breaks free. This is a great way to wear down the boss's VP very quickly.

Surviving The Breath Attack

When Insania Rex gets down to about one third of its health bar, it will sprout wings and fly up to the ceiling of the cave. When this happens, ready your shield and make sure your Stamina and VP are as full as you can get them. If you have any Defense Up items, use them now.

Fly up to the ceiling yourself so that you aren't directly in the line of fire. Target Insania Rex so that you're directly facing the breath weapon, and hold up the shield to parry. If you're close enough, you can continue to fire on the boss while maintaining your guard with a one-handed firearm.

Watch your Stamina! It's better to lower your shield and take a bit of damage while it recharges than to let it hit zero while guarding — otherwise you'll suffer Armor Break and start to lose actual HP!

It's important to note that the breath weapon deals damage over time, rather than hitting all at once. That means that if you do get caught by it undefended, you can use Repair Sprays or Devotion to mitigate some of the damage. In fact, you can even tank the whole thing by just burning through your stock of Repair Sprays; it's not an ideal strategy, but it works.

After the breath attack, Insania Rex returns to the ground and rests for a long time. You can usually finish it off before it starts fighting again, or get close enough that it won't be long when the battle resumes.

Rewards For Beating Insania Rex

Like most Immortals, you'll need to fight Insania Rex several times via the Simulator to really get any major rewards out of the fight. The first time you loot Insania Rex, consider taking its Fusion Factor, which is always a Compound Factor that includes Might-14. Might-14 on its own teaches Subjugation, which lets you take control of nearby Immortals, and it's also a component to several powerful Weapon Skills.

On subsequent battles, you can get Insania Rex's Immortal Cores and the Development Designs for the Dragon Slayer armor series, which the Cores are used to create. The Dragon Slayer set is solid all-rounder armor with high VP and Laser Defense, and comes with built-in Burn Resistance. Technically, that means that fighting Insania Rex gets a little easier each time!