Underbog Colossus

Underbog Colossus can be found in Serpentshrine Cavern.

General
Underbog Colossus are single pulls that come between the Type 1 packs early in the instance. Like the Ancient Core Hounds in Molten Core or the Anubisath Sentinels in Temple of Ahn'Qiraj these mobs pick from a random set of abilities. They will retain whichever set they have until respawn, when they will reset.

Aside from their random abilities, each one has a elemental weakness. Unlike other such vulnerabilities, these ones cause any spell of that element to always critical strike if possible.

Type A

 * Rampant Infection - kind of the opposite of prayer of mending: does 3k or so damage and then jumps to someone (just one person) within 10 yards in 1.5 seconds. Damage seems to go up every time it jumps. Abolish disease or similar can remove it if people are quick enough to catch it before it jumps.
 * Spore Quake - Does ~2k nature damage per tick along with knockdowns over ~12 seconds to everyone within 30 yards. Melee should run out for this (they shouldn't take more then a tick or two of it as long as they don't get knocked down).

Type B

 * Acid Geyser - Does ~2k nature damage per tick over around 10 seconds in a frontal cone to a random player in range. Ranged DPS can out range being targeted since the target range is ~35 yards (shadow priests be careful!). You can not out range the damage if someone in front of you is targeted, the target and damage distances are different.  The Underbog Colossus will turn to face a random person when using this, so you cannot face the colossus away from the raid to avoid people getting hit by it - spreading people out so that not everyone gets it at once is the best way we've found to deal with it.
 * An effective way of reducing damage done by the Geyser is to have all members of the raid stand close to the mob, and keep an eye on who he is targeting. The person who is targeted for the geyser should run through the mob, thereby spinning him around away from the group. However your raid may wipe because of the spore quake...


 * Parasite - Does a ?2k dot to target, after dot a small 1 hp 'parasite' will leave the infected person and go to a new target. Also spawns parasites if a parasite kills someone.

Type C

 * Frenzy - Hunter can use Tranquilizing Shot to make it easier on the healer, although it's pretty much a nonissue.

On Death
There will also be a choice of abilities he might use as he dies:
 * Toxic Pool - When the colossus dies, it turns the ground bright green in a huge area, which does ~2k nature damage a tick if you stand in it. Just run out of the bright green ground and wait for it to fade out.
 * Two Colossus Lurker - Tank + spank
 * Many small adds - Lots of HP so AOE isn't easy. Best practice we found was have the tanks gather them together in a pile, and leave 1 tank in the raid to pickup loose ones.
 * Refreshing mist - blue mushrooms with regenerative properties. Stand in them and be refreshed. (Regenerates 9-11 health and mana every 2 seconds, and some pet happiness).
 * Nothing!

Underbog Colossus can be picked with herbalism, and can drop up to 3 of any type of Outland-based herb including Ancient Lichen, Felweed, Dreaming Glory and even Black Lotus.