7 1/2 ft tall. He's always black and white. The black shading being the black and everything else being white. 
 
Magic: 
• The way his abilities work, it derives from his HP. That's where the energy comes from.
• His main ability is something called "Mook (minion) summoning." Each minion takes about 1/4 of his heath to summon. However if he chooses to push it to the limit, it will take away 2/3rds of his heath AT MAX HP as required. His minions are much tougher than they look, don't expect them to go down in one hit. The minions he summons ranges from being archers, beasts that slash, an archer riding a beast, or any other combination of the 3. The minions are always 3 ft tall. When he summons a minion, he loses his black marks except the black on his hair, he loses 2 ft in height, and the scar goes away. Here's his minions:  
• His secondary ability is barrier break. It drains 10% of his health. This allows him to break through any created barrier from force fields, conjured armor, psychic block shields, and including actual defensive physical shields. An interesting debuff is inflicted onto the opponent called "Flimsy," which heavily weakens any defense-related abilities and defense for 15 seconds. Enemies affected will have a gray and black smoke coming out of their entire bodies, similar to how a fireplace looks after it was burned.
• His third ability, Black Bile. It drains 15% of his health. Black Bile involves him spitting a black substance onto his enemies. It inflicts the debuff "Energy drain." It inflicts minor damage and drains the enemy of their energy quickly for 10 seconds. Enemies affected have black blots on their skin or on their armor. 
• His last ability is Explode. It uses virtually all of his (remaining) heath to cause a devastating explosion. Before he does so, he will release a very mini version of himself which is like his last 1% remaining health, run away (or just hitch hike on one of his summoned minions) from the explosion radius very quickly. Then as his main body gets ready to explode, he raises his arms in air and begins to swell with white light emitting from him for 5 seconds. At the last second, he spontaneously self destructs, an explosion capable of destroying stone, annihilating anything within a 100 yard radius. The explosion looks white and gray. It leaves a crater of anything in the blast. Any survivors (unless you're a hardcore badass) that survived the explosion are left with a debuff called "Survivor's Gulit." This debuff drains individual of their health for 10 seconds, so if you're a person with a "survive a 1 hit-KO" kind of move, the Survivor's Guilt will kill you when you're on your last piece of health. 

Other stuff: He do this such as:
• Slash his opponents. 
• Body tackle. 
• Hurl large debris. 
• Chomp his enemies. 
• Swat with tree logs

• The thing on his back, it contains water, lots of it. If he (or allies) catches on fire, expect him to throw water on him (or them.) 
• To regain his health (or his size if he exploded himself), he will, and must eat meat to gain it back ( or return to regular size). He has a big mouth, suspect that he will devour surrounding fauna, and even people. 

Bio: Despite his look, he is not a glutton. He can go for many days without eating, and when he does, it's in moderation. This big guy is not a talkative person, rather, he prefers to respond nods, smiles, frowns, and hand gestures. When a person decides to tag along, they better not be a talker. But he does enjoy an adventure whether it'd be hiking, exploration, or traveling. During the adventures when coming across fallen travelers in need of help, he'll tower over then and chuckle to himself. Usually because he enjoys the fact he can traverse a long distance through bad terrain such as deserts, mountains full of danger, and so on. After that, Jarvis helps the individual in whatever way. He's a laid back person with a calm demeanor. When it comes to fights, he takes advantage when people see him as someone with a brute like fighting style. 
"You could say I'm a big guy with a brute like fighting style. But actually, you can consider me a specialist. I prefer to turn their combat styles into potatoes. Funny because you're going to be smashed like one." 
He won't have a conversation during a battle. Don't expect him to gloat or show off. 

Rather than looking for treasure, he looks for exotic meats of certain creatures. Many of them, dangerous, his favorite meat is dragon. Probably considered a taboo to many people, he loves the thrill of fighting such formidable opponents. These individuals releasing such immense power. Going on the hunt. When they get drained of all their mana. And finally when they fall as he gives them the killing blow. At last the satisfying savory, tough, filling, and plentiful meat when he gets to bite into them. It makes him fell alive. Because of this, he is nicknamed "Jarvis the Dragon Slayer." Sounds cool to an amateur, until you figure put dragons are mostly sentient like people, and put bounties on your head for eating their kind. Hunting is Jarvis's second favorite hobby. 
Because of his black and white unnatural look, people conceive the idea that he is some evil being. A demon even. In reality, he's neither, but what he is, he will never tell you truly. "Holy" men usually attack him on site, villagers throw things at him, and knights try to slay him (then end up failing.) Village forms an angry mob? He will not hesitate to kill them all using his minions and his own strength. Guilt? Ha nope. 

He does not disclose much about his past. But the most a person can get from him is how he supposedly "has no soul." Jarvis will tell in a form of a joke. 
"'Hahaha, I'm going to consume your soul!' The witch said. 'Sorry lady, I already gave my soul to someone else.' I replied. 'To whom? The Devil? Demons? Someone already took it?' Questioned the witch. 'Nope, something worse.' ^_^."