Sigma is the newest Hero coming to Overwatch and is an exciting addition to the hero pool both in terms of lore and play style. He is a main tank, filling the same role as Reinhardt and Orisa, and therefore offers a strong new option for one of the most important roles in the various Overwatch game modes.
Jeff Kaplan, director of Overwatch, describes Sigma as a 3-star, or highly difficult character to play. He anticipates that skilled players will need some time to learn Sigma's abilities and get a feel for his power level, but once they do, Kaplan suspects Sigma will be a force to be reckoned with on the battlefield.
This beginner's guide to Sigma and his ability kit will help you get started once he becomes available to play in the game. If you want to get a head start, you can download the Overwatch Public Test Region and start playing Sigma right away.
Hyperspheres
Sigma's primary fire ability launches a pair of explosive spheres from his hand that can bounce off of walls and detonate after a short delay. These spheres have a bit of tracking, but not enough to follow enemies around corners or anything like that. Instead, they're more for flavor and sell the idea of gravity and magnetism from a flavor stand-point. Though the spheres fire in two round bursts, Sigma has unlimited ammo.
These spheres fire similar to Zenyatta's orbs but with a range closer to Roadhog's right-click. They seem to be especially good in tight corridors in which Sigma can fire them over barriers and bounce them back and forth down hallways. You can try to catch your enemies indoors for maximum damage with the hyperspheres.
Experimental Barrier
The RMB ability sends a square barrier shooting out from Sigma, which is similar in size to Reinhardt's barrier. It is similar to the Symmetra's barrier from her second iteration, but with more function. Releasing the barrier at any point will stop it from moving, while pressing the right mouse button again will return it to Sigma to be redeployed.
This is more forgiving than Orisa's projectile barrier because Sigma can reposition the barrier without having to wait for a cooldown. It also has 1500 health, which, like Reinhardt's shield, will only recover while it is not out on the battlefield. You can use it to protect teammates at different elevations and in places you can't get to yourself, as it moves fast and can be positioned at any distance.
Kinetic Grasp
This ability allows Sigma to freeze incoming projectiles in the air and convert them to shield. It's similar to Zarya's bubble, but it is different in the sense that it only absorbs projectiles and not, for example, Reinhardt's hammer or Doomfist's fist. Sigma can store up to 400 shields on top of his natural 300 health and 100 shield, so, with proper timing, there is potential to quickly beef up for a team fight. Zarya players will definitely have an advantage anticipating burst damage to get the most out of this ability.
Accretion
Sigma gathers up a boulder and hurls it at the enemy, dealing significant damage and knock down. This ability has a few seconds of wind up time, so you won't want to cast it in a panic (save your kinetic grasp for that). Instead, try to use the Accretion to finish off low health enemies or break weak barriers. It is somewhat slow-moving but has a large hit box, so this ability will be the number one power to practice aiming in the training room with.
The knockback in Accretion makes Sigma yet another booper, so try to use this ability to displaces ulting Mcrees, Pharahs, and Moiras. It can also be used to knock enemies into the pit in Illios, obviously, and this should be your #1 goal.
Gravitic Flux
Finally, Sigma's ultimate allows him to soar into the air, similar to Mercy's ult, before targeting a large area on the ground, like Doomfist's ult. Any enemies caught in this field will be launched into the air and held there for two seconds. This is your team's opportunity to lay on the damage as your oponents are not only CC'd but are also lifted in the air without any cover.
After two seconds, the enemies will be slammed onto the ground, dealing 50% of their max health as damage. Because you are flying, you can also use this ability to reposition, though it shouldn't be used specifically for that purpose.
Put It All Together
Sigma is a low mobility, high skill character with strong team synergy. He is the tallest hero and is vulnerable because he has no way to escape danger. Luckily, Kinetic Grasp and Experimental Barrier should give him some strong sustain and Accretion will make him formidable in a team fight.
Sigma should be played as an offensive main tank, able to push the payload forward by constantly repositioning his shield and keeping the pressure on with Accretion. You'll also want Sigma to use his stature and Kinetic Grasp to soak as much damage as possible for his team and use that devastating ult to turn the tide of team fights in your favor.