Guthan the Infested is the third oldest of the six Barrows brothers. He attacks with melee using his warspear. He attacks at a fairly average/slow speed, but despite this, he can still deal around 1000 damage per hit and should not be taken lightly, despite being regarded as one of the weaker Barrows brothers.
Guthan's set effect: Guthan's Infestation, allows him to heal himself at a 1:1 ratio, so if he deals 500 life points of damage and the effect occurs, he would recover 500 life points. His effect is accompanied by an animation when activated; three ghostly entities surround Guthan's opponents then circle around them in an upwards motion.
Guthan's crypt is located at the south-east of the Barrows area, and he is weak to Air Spells. Strong magic spells such as Air Surge, Polypore Strike and Smoke Barrage are recommended when fighting him, however he can be taken down just as easily with strong melee weapons such as the Chaotic Maul. Guthan does not pose as much of a threat as his brothers do, with his set effect healing him instead of dealing extra damage or draining stats/adrenaline, but players should still be cautious and well-prepared when fighting him.
Guthan returns with his 5 brothers in Barrows - Rise of the Six, greatly enhanced by Sliske's experiments into the Shadow Realm. As when fought normally, he retains his set effect, and also has various other abilities.
As with each of the other brother fought in the Rise of the Six encounter Guthan can drag a player into the Shadow Realm.
As with Dharok, Torag and Verac, he can perform a spinning attack that rapidly damages close target while chasing his main target.
Guthan's Spear throw will target the player that is not his main target on his side of the arena. While impaled that player takes consistent damage over time until maneuvers are taken to place Guthan beside the impaled player, in which the spear is recovered. While Guthan is without his spear he will continue to attack using punches.
Guthan, along with all the other Barrows Brothers, received a graphical update on 4 January 2012 to make him look more like a player wearing his items rather than the old graphics style which displayed an unclear, purely pink coloured apparition. Along with this update, his combat level was increased from 115 to 147. Due to the Evolution of Combat his combat level has once again increased to 150.
When Guthan's face disappears, most of the face will disappear, but after a tick, a small black shape will appear, and disappear in the next tick. It is possible for the shape to stay for a very long time, and therefore Guthan's face will appear constantly until the shape disappears.
Guthan, along with the other Barrows Brothers, have not received any animation updates since the Evolution of Combat - leaving them to have old attacking and defending animations.