The Colossus (or Dreamy) is the final boss of the Shadow Arena
Colossus will always have at least 1 passive buff, and can have a max of 3 buffs, Colossus' strength varies based on the Uber arena level.
Colossus' buffs and tips:
Teleport - Teleport is the hardest buff to deal with, as he can teleport to anyone on the Arena, so it is recommended to group up your team in one point on the arena, them everyone can hit the boss and kill him fast.
Bee - The Bee is the most useless buff for Colossus, as the bee has low HP and damage. It doesn't scale with the arena level as well as the other mobs, so you can kill it very fast.
Poison - The Poison buff allows him to use the poison bomb (the same attack from the purple mushrooms). You should avoid this poison at any cost, because it deals a percentage of your health ( ~20%) as damage.
Lore
"The Defender of the Arena. The All mighty Colossus, a huge creature of amazing power that smashes any Trovian that opposes him.
Legend has it that this creature once ruled over the land but four heroes, a Knight, a Gunslinger, a Fae Trickster and a Dracolyte managed to imprison it in a Shadow Realm. Now it only serves as a symbol of fear that destroys every challenger who tries to conquer the Shadow Arena. Will you become one of the heroes that triumphed and remained immortal throughout history? Or will you be one of the countless victims that were crushed beneath this creature's mighty shadow?"