This page of the Outriders guide contains a walkthrough of the Molten Acari boss fight. You will learn when the fight occurs, what attacks you may expect of him and how to avoid them as well as how to defeat him effectively and quickly.
The fight with the spider takes place during the Inferno main quest. This is the second major fight in the game. You will have to use the enemy's weak points to your advantage.
Most of Molten Acari's abilities are area-of-effect attacks, with occasional round attacks targeted at a specific player and the summoning of minor arachnids that act more as ammo refills than real threats.
This attack is relatively easy to dodge. The spider always has to approach the edge of the arena first to perform it. During this attack there can be 2 difficulties: minor arachnids can attack and the area the boss is targeting is often poorly visible.
There is also a completely different fire attack that occurs during the second stage of the fight as pictured above. Molten Acari attacks in a straight line in several directions. Very easy to dodge, doesn't inflict much damage. During this attack, he will also summon smaller arachnids to fight - once killed, they will drop ammo.
Combined area-of-effect attack
This is a variation of the basic area-of-effect attack around the boss, except that in this case it additionally sets the arena on fire in different directions in a straight line. Keeping an eye on the blue markers will help you avoid the attacks of Molten Acari. After this attack, the boss tends to slowly approach the attackers. Fortunately, straight-line burning doesn't last long.
Acari can perform a round attack while in the arena as well as on walls, as in the picture above. Then, it launches rounds towards the players and they will break into 3 smaller rounds after hitting the ground. They don't cause much damage.
Every now and then, an arachnid will try to jump on players, from the arena and from the walls. This attack deals a lot of damage, so you have to be especially careful of the boss's actions. The attack is relatively easy to dodge if you are in constant motion.
They occur in two stages of the fight. In the first stage, the arachnid will try to perform a combination of 2-3 close-range punches if one of the players gets too close. In the second stage, Molten Acari selects the locations to attack randomly, as pictured above. Theattacks are quite easy to dodge, but inflict a lot of damage.
In addition to avoiding vulnerable sectors with blue markers, focus on shooting at Molten Acari's weak points. Of course, you can also shoot anywhere, but then the boss takes much less damage.
The spider has its weak spot on the abdomen, as pictured above. If you use a sniper rifle, you may destroy the armor even with just 1 shot, but sometimes you will have to shoot up to 3 times. Once the armor is destroyed, the enemy will take more damage and be more susceptible to critical hits (at a level like the one pictured above, you can sometimes get 2,000 damage with a single sniper shot). Armor will regenerate repetitively.
The second stage of the fight operates on the same rules as the previous one: only the location of the weak point changes. It is located by the creature's head.
When it comes to class skills for boss battles, you should consider offensive moves, area-of-effect moves and moves that rely on increasing mobility. As an offensive skill, it's worth choosing improved rounds (3 classes have a similar skill - Twisted Rounds, Volcanic Rounds, Blighted Rounds) - it will be easier to deal significant damage to weak points and pierce armor. Area-of-effect abilities will help you take down smaller arachnids, while mobility abilities will serve as a backup if dodging attacks gets more difficult.