-This guide is simply a 'how to' beat the colosuss.
You will fight the Ember Colosus in Tu'tara Caverns in the Vast Chasm. This is comes after floor 19.
As always there will be a short cutscene and then the fighting will commence. As stated by Insanity, he has a strong beam attack and then resorts to melee.
I will tell you now that I was thouroughly dissapointed in this boss battle.
I play as the Alchemist. I changed my Pet to a dog (though any fish will do) and I also summon a Golem to fight beside me.
I preferred speed over powerful attacks. As such I have a wand in one hand and a pistol in the other. At the start of the battle I cast Ember Shield (in case he charges me) and Ice Shock to slow down the Colossus and the surrounding enemies. I then cast my Summon Zombies. (these give hp everytime they land a hit, and 3 are summoned). Immediatley after that i simply held down the X button.
In 30 seconds the fight was over. I never used a single health, or mana potion. I was Level 17 when i fought him (you will most likely be 18 if you did side quests).
If you are unable to summon creatures, then focus on what your characters strengths are. As always potions are a huge help.Both Vanguisher and Berserker have skills sets of freeze, and heavy hits. I'd suggest using those same variations.
--Obviously with the Vanguisher keep your distance. Shoot a Frost Pilum to keep him from getting in 3 hits before your first trap goes off. Speaking of...Summon traps OFTEN and don't be ashamed that your not fighting him face to face. Surround him with traps,all the while blasting him with your bow or double pistols and he'll be dead within a minute.
--If your the Beserker do what you do best. Feel free to charge in there! Cast Frost shield, summon an archer and hack that giant down to pint sized toy soldier. WARNING: If you charge him you will be surrounded by his little minions. I'd stay focused on him. The guys are easy to take out, but are simply a distraction while fighting. Use Titan Stomp to clear some space and keep hacking. You'll have him dead in a faster time than me.