The Arch-Vile in Doom 3 is a relatively high-level demon, possessing more than three times as much health as an Imp. As with its previous Doom incarnations, the Arch-Vile can be easily underestimated. Though not nearly as durable as "powerhouse" creatures like Hell Knights or Mancubi, the Arch-Vile's varied attacks and ability to summon other demons make it one of the toughest enemies to defeat, for it will instantly summon demons after its appearance (most commonly, far away from the player's position). Many players feel the Arch-Vile needs to be killed as soon as possible, often with the Soul Cube, the BFG, or the rocket launcher.
Fortunately, Arch-Viles are usually encountered alone, although they can quickly summon additional demons as backup.
The Arch-Vile in Doom 3 largely looks similar to its Doom II counterpart (especially in the face and elongated forehead/skull), still emaciated, but does not have the sunken stomach, and has a different more greyish skin pigment (and its hands look more diseased, but still end with long fingers/claws). It is a large, off-white colored humanoid demon, standing a head taller than a normal human even in its standard semi-crouched pose. Its elongated arms are both terminated in bloody, tumor-like, bloated hands with huge, inward-retracted claws, giving the impression the monster is wearing glowing boxing gloves.
Though it cannot revive defeated enemies like the classic version, due to their bodies burning away instead of leaving a corpse (interestingly, when the player kills the first Arch-Vile encountered in the game, its corpse doesn't burn away. This doesn't happen with other Arch-Viles encountered later in the game), the Arch-Vile makes up for this by being capable of summoning (i.e. materializing) many of the non-boss demons (though Imps & zombie commandos are more common, Cherubs and Wraiths have also been noted and it will also summon Hell Knights in later Doom 3 levels, and Maggots in The Lost Mission). It can also slash its victims at close range, as well as unleash a fast-moving column of hellish fire that can seriously hurt the player, causing up to 20 points of damage. In some special cases, it is capable of making the ground erupt in flames underneath the player, similar to its original attack, but this time it's possible to dodge it, although it requires that players constantly be on the move. First examples are encountered in Delta Labs Sector 2.
Charging the Soul Cube with the Arch-Vile's minions is the only reason to hesitate in attacking it (this should be considered by advanced players only). Otherwise, killing the Arch-Vile should be a top priority. At long range, the Soul Cube and the BFG are the best weapons, and a two-point projectile is recommended. Arch-Viles are very slow compared to earlier versions and use no projectile weapons, making it impossible for them to shoot or evade the BFG projectile. Also effective are the Chain Gun, Plasma Gun, and Rocket Launcher. The Machine Gun is not recommended, since it requires almost a full magazine of direct hits to kill it. At close range, the Shotgun or Combat Shotgun (Resurrection of Evil) are recommended. At this range, it will usually take three or four shotgun blasts, but it is just barely possible, though extremely rare, to kill it in two. Another tactic is to rush the Arch-Vile with a Chainsaw while it's summoning its minions, as it will be vulnerable.