Ahrim's set effect, Ahrim's Blight, gives each successful attack cast by Ahrim a chance to lower a player's Strength level. Although the damage from the attack itself can be partially blocked by protection prayers/curses, the set effect cannot. Therefore it is advisable for a player to bring something to restore a player's Strength level back to normal if using melee, such as a restore potion or greater. This effect is accompanied by an animation as well as a sound effect.
Ahrim's crypt is located in the centre of the Barrows area, and he attacks with magic, casting Fire Wave with his staff.
Ahrim is weak to arrows, therefore strong ranged weapons such as the zaryte bow, crystal bow, dark bow or magic shieldbow (sighted) are ideal. Lower levelled bows are not recommended due to his high Defence level and due to low levelled bows not being powerful enough. Ahrim has a tendency to cast Curse spells much more often than his Fire Wave, so using melee is not advised unless the player has a lot of stat restoring potions, or is under the effects of an overload potion.
Using the curse Soul Split can also restore some life points to those who can use it, due to the fact that he does not cast Fire Wave as often as his curse spells, though a player must watch their life points just in case.
Ahrim returns with his 5 brothers in Barrows - Rise of the Six, greatly enhanced by Sliske's experiments into the Shadow Realm, and this time attacking with blood spells. As when fought normally, he retains his set effect, and also has various other abilities. These include:
Energy Blast: Ahrim spins around with flaming energy releasing from his hands. If close enough to Ahrim and you are hit by a beam you will be dealt 1500 damage per tick. Additional damage is dealt if you are very close to him. Ahrim remains still while he does this.
Sky Jump: Ahrim levitates into the air for a set duration, evading melee attacks and reducing any magic damage he takes.
Teleport: Ahrim teleports to the top of the battlefield, attacking targets from that location. While in the air, Ahrim is immune to melee and damage dealt to him through magic weaponry is reduced by half.
Gas clouds: Ahrim will sometimes spawn gas clouds which deal rapid damage to players standing on them. Their colours are purple and red. Players should be extremely careful to keep the brothers away from the red clouds as they will rapidly heal any brother standing on them.
Shadow Drag: Like his brothers, Ahrim is able to drag player teams into the Shadow Realm. While in the Shadow Realm, Ahrim and all of his brothers will gain enhanced damage and accuracy.
Ahrim, along with his brothers, makes an appearance in Kindred Spirits. Sliske puts him through a "game" of righteousness where he navigates through the maze and makes decisions (either by himself or the player) to reach the centre of the maze.
When Ahrim arrived at the centre of the maze, Sliske dropped a druidess named Isolde, the player and Guthan inside. It is shown that Ahrim had killed Isolde to "protect" Guthan from her "godless" faith, although it is shown that he killed her out of jealously. If Ahrim was bathed in most of the blue flames, Ahrim realises that he had been arrogant the whole time and asks for forgiveness from both Isolde and Guthan. If Ahrim was not bathed in most of the blue flames, he kills Isolde again.
Ahrim, along with his brothers, appeared in Sliske's Endgame, being the second intended wave in Sliske's attempts to destroy the World Guardian. However, the Barrows Brothers had managed to regain a modicum of control over their own actions, and chose to aid the World Guardian, attacking Sliske's wights and champions.
Ahrim, 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 the graphical update his combat level was raised from 98 to 130. It was changed again to 150 after the release of the Evolution of Combat.
If an empty bucket is used on the well next to the Barrows, Ahrim will pop up in a combat stance and then disappear. Your game box will then say "For some reason, Ahrim pops up and fills your bucket with water."
Ahrim has access to all spellbooks. In the original Barrows, he uses Fire Wave and curses, in Rise of the Six he uses Blood spells, and when filling the bucket with water he uses Humidify.
There is currently a graphical glitch where Ahrim uses a water spell animation when casting Fire Wave in the normal Barrows encounter, making it seem like orange-coloured water forms around his hands.