Sevarog is a Growth/Corruption affinity Hero that is advertised as being a able to excel in either a Tank or Jungler role. His Passive ability "Soul Tap" allows him to build stacks of souls. Each stack gives him +3 max hp, and his model grows larger and more detailed at 20, 40, 70, and 100 stacks. His Q ability "Siphon" deals physical damage in a line in front of him. Killing a minion with this ability gives him +1 soul stack, while killing a hero gives him +3, and the ability gains a damage bonus every time he grows from collecting souls. His RMB ability "Phantom Rush" let's him dash forward and ignore unit collision, although terrain and Dekkers wall still impede his movement. His E ability "Subjugate" is a long range, small AoE that applies a snare, and then a slow while dealing physical damage. His R ability "Colossal Blow" lets him hit enemies in a cone in front of him, instantly killing minions and launching enemy heroes back a long distance.
Because of his Q and Passive, he should be spending a lot of time farming minions, although due to his complete lack of any real damage if you build him tank, last hitting with his Q and getting soul stacks can be quite a chore, especially considering the cool down it has in earlier levels and the difficulty in setting up killing multiple minions simultaneously with one cast. Once you get him going, however, he becomes a walking (hovering?) fortress that can soak up tons of damage and provide CC to melee carries, and knock ranged heroes towards his allies to be slaughtered. However, as I said previously, if you intend on building him as a tank, forget about getting kills. You do so little damage without furiously spamming your Q and E (and eating up your energy in the process) that you'd be better off just farming until your team needs you to become a meat shield.
I foresee Sevarog becoming a highly effective support, however, simply due to his CC abilities. If you build him as a tank, you can body block shots for your ADC, snare the enemy carry so that yours can get some free hits in, or dash behind them for a quick flank and them ult them under your tower if they push to hard. The range on his E is absolutely terrifying, and a skilled user will be able to zone out tanks or melee carries during a team fight just long enough to kill the squishies and tilt the fight in to his teams favor. I'd say practice on landing his E and using it in various situations, and then don't even worry about farming souls, just use tank cards and max out his E first if you want to be extremely obnoxious to the enemy team. The uses for a flat out hard CC are endless, especially in Paragon where heroes like Grux and Feng Mao dominate the lower ELO's due to high mobility and brutal melee damage.
For items, I would highly recommend building a lot in to CDR and Mana so that you can spam your utilities more often and for longer periods of time. Sevarog really doesn't seem like the kind of guy who wants to be in people's faces crushing people. He seems to me to be more of the cold, calculating type who enjoys manipulating the battlefield. I'd say better to have somebody like steel or rampage fill the tank role, and have Sevarog be built as a control mage. That's not to say don't give him survivability, as you want to be able to survive dashing in to ult squishies towards your team or your towers if you're able. Use your Q to last hit minions as they come buy, and rely on your E to control the battle field and win each fight for your team.
If you're planning to take Sevarog in to the jungle, I HIGHLY recommend taking some cards to give yourself more physical damage and attack speed. Sevarog does so little damage that his clear time will be extremely slow, although farming with his Q will be much easier. Still build in to items that give him HP and Mana, with a little CDR splashed in for good measure. Only go full tank if you want to stand in the middle of everybody getting shot so your team doesn't and do practically nothing else. Give him some love in other areas to make sure he can actually use achieve his high utility potential.
All in all, after playing with him for a bit, my personal opinions are mixed. On the one hand he looks totally badass and has a lot of neat abilities, but on the other hand I like damage dealers and his performance in that area is so underwhelming that it's almost boring to me. Nothing he does feels like it has any impact behind it, and his pushing power is almost non existent due to his slow wave clear time. I feel like even though Epic wants to say he's a tank and a jungler, I feel he'll really shine when used by skilled support mains who can take advantage of his CC to manipulate the field to their advantage. I'll have to play with him more and mess around with his kit, maybe build a few decks just to see what all he can do, but as it stands he's not at all what I expected him to be, and there's a lot to be desired with this hero for me. That doesn't mean I won't play him, though. I used to think Anivia was one of the worst champions in League of Legends until I started messing around with her ou tof boredom and saw what she could really do. Now I own her Blackfrost skin, have level 5 mastery, and have been maining her in the mid lane for 2 years now. Maybe Sevarog will be my new Anivia?
HAHAHAHAHAHAHA nobody will ever replace my bird.
Not even a pair of disembodied arms wearing a cloak and holding a hammer with a bunch of neat CC abilities.
(If you'd like to try out Sevarog for yourself, you can purchase a Founder's Pack for Paragon for $19.99 here: https://www.epicgames.com/paragon/founders, or you can wait until summer when the game goes in to Open Beta.)