Seth is the deranged madman driving a gigantic mining walker outfitted with high tech drilling equipment. Most likely insane from the horrors of the Apollo Outbreak, Seth was presumably the walker's previous operator. It is protected by thick armor to keep the rig and its operator safe from hazardous working areas. Physically, the mech is a large walker that sports twin concussion grenades launchers originally designed to blast away rock.
Seth is unavailable in Recruit, but replaces Zeus and Leto in Normal/Hardened/Vet or Nightmare difficulties. The Mineshaft is available in every campaign including survival. Seth is not necessary to complete the campaign, but his rewards can be helpful. To activate him, two players must simultaneously step on the Abandoned Mineshaft hexes. He can be awoken at any time up until a campaign's completion.
Like the Queen herself, Seth can have excess of 100,000 health on higher difficulties. His main attack is his concussion grenades, which are painful, but slow. They do have a slowing effect making it hard to escape if he hits you. However, thankfully Seth is quite tankable. Any player with 7 or more armor can tank his main attack with good results. This includes Demo Tanks and Flamethrowers with XS-4 Armor, or any tanking class with Kinetic Armor, Reactive Armor, or C4. However, that's not all. During the fight Seth will assign polarities to every player. If similar polarities group together, they receive bonus damage, stacking up to a 400% increase. If they stand close to an opposite polarity, they shock each other for 35 damage per second. This can quickly kill weaker characters. The polarities switch roughly every 13 seconds (8 seconds in Nightmare Mode). After the second Polarity Shift, Seth unleashes his Ultimate Attack, his Plasma Detonator. This is an expanding energy blast that deals 150 damage and bypasses all known armor except the damage reducing affect of Kinetic Armor. It will outright kill many lighter characters if they are already damaged or their shields are down and they do not have stats in Endurance and Strength. The cycle will repeat indefinitely, 2 polarity shifts, then a Plasma Detonator blast up until Seth is killed. The blast starts at a 8 radius and will increase by 2 for each progressive use. This blast has a maximum range of 14 radius, which is so large it no longer can be properly displayed. After the third blast, it is advisable to run far and fast after the second polarity shift or use a Medkit. Once finally killed, Seth will drop a large cache of ammo to replace what was used in the fight, as well as an H3 Canister and a special reward.
Seth leaves behind a small bounty of rewards when killed.
When defeated, Seth leaves behind a Helium-3 Canister. This will add to the Credits of any surviving players. The player who physically retrieves it does not get more credits than his companions; but dead players do get nothing.
When killed Seth will leave a large pile of Magazines to replace those expended during the fight. If killed quickly and efficiently, this ammo will have a higher net value than the ammo used. If the fight drags on, the ammo may not be enough to cover your loses.
Seth leaves behind one of the following items when killed, each with a 25% chance of dropping:
Seth's primary attack slows the targets movement speed greatly, making it hard to escape once hit. This attack also does a small area of effect damage and slow.
Seth will periodically summon repair droids to heal his injuries. They heal incredibly fast, at a rate close to 150 health per second, and should be killed immediately.
Seth unleashes a blast of pure energy that deals 150 damage in a radius around him. Each blast will be 2 radius larger than the previous starting at 8 and maxing at 14 radii. The screen will turn a blueish hue and the player will see the ever expanding blast before it explodes.
Seth's plasma power system interferes with the marines' power armor, infusing them with charges. The charges are + and -, and are denoted by a symbol above the marines' heads. Each marine fighting Seth will be assigned either a positive or negative polarity, and these polarities switch every few seconds when fighting him. Marines with opposite polarities create destructive interference when they get near each other, destroying their power armor and severely hurting them at a rate of 35 health a second. Marines with the same polarities create constructive interference within their power armors, enabling them to fire with much greater power than before. Each marine with constructive interference who stand next to each other will gain a 100% boost upon their attacks to a maximum of 400% boost.