Piotr Rasputin grew up on a farm in Russia until Professor Xavier recruited him to join the X-Men. He is a loyal teammate, using his powerful armored form to protect his comrades in battle. His great physical strength conceals his quiet soul as an artist.Marvel Source
Piotr has an on-again, off-again romantic relationship with fellow X-Man Kitty Pryde. His sister, Illyana Rasputin, is the mutant sorceress known as Magik.
Gear
Slot 1 – Mighty Fists of the Juggernaut (Colossus Unique) - Yup they are awesome. They have a frenzy proc on them, +5% attack speed per attack that stacks up to 5 times for 25%. Its incredible. Also def, damage (of course), +to his amazing punchy skills, +1 Fighting. Just wow.
Slot 2 – Kitty's Favorite Shirt (Colossus Unique) - So. So tanky. So it makes you super tanky, gives you another +1 stat (Speed-hey...might be good soon), health, invuln, and then the big one..+2 to all powers THEN + to Mutant Powerhouse powers on top. So again, all of his punchy powers.
Slot 3 – Dynasty of the Rasputin (Colossus Unique) - Amazing, amazing tank item. Then +2 to powers, and ANOTHER +1 stat (Strength). We're 3/3 so far and its amazing.
Slot 4 – Courage of Colossus (Colossus Unique) - Good tanky item, with +4 to Bold Comrade powers. This helps out our aura, and is generally useful. What's really important here is the damage to bosses (free SG synergy or Odin Blessing practically) and crit/crit damage. Note: As per @Naugrin 's suggestion, Footstigons also make an awesome foot slot! Damage rating ftw!
Slot 5 – Generation Next Bandanna (Colossus Unique) - Serviceable quality of life unique, the +1 to all powers is a little meh, but the damage rating, and movement/attack speed is pretty good. We're already at diminishing returns just with our Slot 1, however, so I'd consider replacing this with a boss cosmic that gives +to your silly passives in the middle tree to help you fill stuff out.
Artifacts
Artifacts: We need points for our crazy passives. Advanced Meta, regular Meta, then whatever you need. I actually like Kargul for crit+crit damage since he does have decent crit. Advacned Crimson Crystal is pretty much a must have. Health/damage is awesome.
Advanced Crystal
Advanced Meta
Meta
HoD / Xerogen / Kargul / etc.
Other
Blessings: Odin helps Colossal Punch stomp bosses even harder. Hela makes him brutal ridiculously, and he crits fairly often-the problem is he attacks slow. Up to you.
Costume: +1 Fighting +1 Strength.
Insignia: O'Gradysaurus Rex with damage. Meh, your call really. I find with Insignias its hard to find stuff in the wild you want-and I wouldn't go out of my way in a lazy build to suggest you trade for "optimal".
Legendary: Gungir or Excalibur. Depends on what you need, as with most of my guides. Shocker. Norns eventually maybe? We'll see how the rework pans.
Medallion: I think Cosmic Kingpin is pretty good here, health/melee. Seems solid for him.
Relics: Probs Lemurias. I know I recommend them in almost every guide, but its because I prefer the utility over marginal stat increases. Like a small stack of these is the Rank 5 Affix on an Excalibur, and goes a long way to keep you alive and well. But whatever you feel you need here.
Leveling Strategy
So you get Osmium Punch and Crushing Smite right away. Once we unlock Colossal Punch, spec into it as opposed to Crushing Smite. Okay so you can kill everything in the game. Oh look, you just unlocked Demolition Stomp at like before level 10. Ermagerd, everything is dead. Put stuff into passives and keep those maxed-GG.
Playstyle
1. So until later this year you get to yell "IM THE JUGGERNAUT". Do it at your screen, feel OP. Osmium Charge into mobs.
2. Okay so you're in mobs now. Hit Colossal Roar and watch trash vanish and clean up with Demo stomp. Blues and Yellows as well as bosses -may- be left.
3. Hit Colossal Punch until you run out of spirit.
4. Osmium Punch until you have moar spirit for moar Colossal Punch.
5. Go to your parade in Red Square (Odin's Palace)