With the introduction of COX i thought i would do his quick guide on how to solo the great olm.

Deaths are considered safe for all players (including Hardcore Ironmen )

Mechanics:

Standard attacks: Olm has two standard attacks: Magic and Ranged. The magic attacks are large green orbs, while the ranged attacks are smaller chunks of crystal. Both deal the same amount of damage. Prayer reduces the damage by roughly 75-80%.

1-The mage attack

      a big green ball

2-The range attack

      a small green crystal

Spheres:

Olm randomly picks a sphere (red, green or purple) and sends it at the player. If not blocked, the player will be damaged approximately 50% of their current Hitpoints. If a protection prayer was used when the sphere was launched, it is disabled and the player's Prayer is reduced by 50%. To block the attack, pray accordingly before and as the sphere hits you:

   Red (sphere of aggression): Protect from Melee
   Green (sphere of accuracy and dexterity): Protect from Missiles
   Purple (sphere of magical power): Protect from Magic

During phases 1-3, Olm also has access to these specific attacks:

1-Lightning :

Shoots out lightning running north and/or south of the chamber. Getting hit by a bolt of lightning electrocutes the player, disabling their overhead prayers, dealing moderate damage, and binding them. The left hand will briefly show a lightning bolt when using this attack.

2-crystal burst :

Olm throws a crystal seedling under every player in the chamber. A few seconds later, the crystals burst and shove the player to a nearby tile if they are on top of them for heavy damage. The left hand will briefly show a crystal icon when using this attack.

3-Swap :

Olm will perform a teleport attack that deals damage the further the player is from the target. The left hand briefly shows a swirl when using this attack. If alone, Olm will pick a random tile anywhere in the chamber; if there are more players in the room, Olm will evenly distribute the amount of teleports. If there is an odd-numbered amount of people inside, then those people will not be subjected to the attack.

Olm also has phase-unique attacks which can replace one of the auto-attacks in his rotation:

Acid:

Acid Spray: Olm spits out several pools of acid around the chamber. Standing on top of an acid pool deals 3-6 damage per tick and inflicts poison starting at 2 damage.

Acid Drip: Olm covers a player in acid, causing them to generate acid pools under them. Standing still will deal damage and moving will generate more pools, though it is not much of a deal in small groups. The pools function the same way as the pools in the spray attack.

Flame:

Deep Burn: Olm shoots out a green fireball at a player, causing them to yell "Burn with me!". The targeted player takes 5 damage every few ticks, dropping stats by 2 each time this occurs for six hits. If it spreads to other players, the timer resets and newly infected players will initially yell "I will burn with you."

Fire Wall: Olm shoots out two walls of fire at a player to trap them. If the player is on a tile that would be occupied by the fire wall, they will leap out and take 8-10 damage in the process. After the walls are placed, players in the tiles between the two walls will take 50-65 damage in 5 seconds if they do not escape. Any water, such as water spells, ice spells, Humidify or a filled watering can will suffice in dousing a segment of flame.

Crystal:

Falling Crystals: Olm lets out a cry, targeting one player with a red aura. 11 spiked crystals fall from above, dealing up to 15-20 damage to anyone in the targeted tile.

Crystal Bombs: Olm shoots out a crystal bomb (up to three at most; two for smaller groups). The bomb explodes after being deployed for several seconds, covering a radius of four tiles. The minimum amount of damage dealt is 15, increasing by an additional 15 damage for every tile closer to it.

There are also attacks applied during other segments of the fight:

Autoheal: During the first three phases, any attacks aimed at the head are completely healed after several ticks have passed. In the third phase, the left arm also gets a variant of this ability where any attacks that deal damage will cause it to heal instead. When this is performed the left hand shows an infinity symbol.

(as you can see the olm's hp is staying the same because it's healing)

Falling Crystals: During phase transitions and the last phase, Olm causes chunks of crystal to fall from above. These crystals have a 3x3 AoE; getting directly hit (underneath the shadow) by them will deal 16-25 damage, while getting indirectly hit (one tile from centre) deals 10-16 damage. One crystal will always be aimed at a random player in the chamber. A shadow will indicate where the crystal will land.

Life Siphon: In the last phase, Olm will shoot out two blue projectiles which generate a shield when it hits the ground. Several ticks later, Olm will damage anyone not on the targeted tiles for moderate damage, healing himself for five times the total amount of damage it deals to the team.

(notice how olm healed because i didn't stand on the blue healing pools)