Arctus is a mysterious character, and an antagonist in Requiem of Agony. His body resembles a suit of armor. He has no arms, only floating gauntlets, and no legs. He has a floating head that rotates and has three identical faces.
Arctus is first fought in the Underground Aqueduct, as the fourth boss. He floats in the air, high above reach. He can send one of his gauntlets down to punch, shoot energy bolts downwards, and summon a symbol that rapidly shoots fireballs of fire, ice, and lightning. He occasionally tires, floating to the ground to recharge, leaving him vulnerable. After his health is reduced by a quarter, he flees, and shatters the ceiling in an attempt to drown the player. Later, he is fought at the end of the level, and the water stops rising. He has the same attacks, but can also summon beams. He has 4000 HP, and his theme is Death Ballad.
He badly defeats the hero, Jason Steele, but he does not kill him, and instead flees.
Arctus fights Steele later in the Tymeo Mountains, revealing his intention to revive Vadriel. He has all of his previous attacks, as well as freezing mist and lightning. Everything else remains the same.
Arctus, once more, does not kill Jason, but before Arctus can flee, he is injured, and apparently killed.