Bio Armor is a Primary Power Set for Tankers, and a Secondary Power Set for Brutes, Scrappers, and Stalkers.
Your body is encased in a durable biological armor that evolves based on your environment. You siphon genetic material from your foes to empower yourself, and eventually you can transform yourself between three Forms.
At 1st level, you can cause thick, interlocking shell-like plates to form all over your body. You gain resistance to bludgeoning, slashing, piercing, and necrotic damage, and any Saving Throw you make in opposition to being stunned or being put to sleep has advantage. You don't need to spend an Action to activate this feature but you can only do so on your turn, and it will deactivate if you fall unconscious or become incapacitated, or until you choose to turn it off.
You can use Environmental Modification at 1st level if you are a Brute, Scrapper, or Tanker, and at 4th level if you're a Stalker. You can use Evolving Armor at 2nd level if you are a Tanker and at 4th level if you are a Brute or Scrapper. You can use Ablative Carapace at 3rd level if you are a Tanker and at 6th level if you are a Brute, Scrapper, or Stalker.
At 1st level, you gain 2 hit points per level, and you can recoup any Endurance Die roll that comes up a 7 or 8 (see the Stamina under Fitness). You add your Constitution Modifier to any Endurance Die result you roll. You also gain advantage on any Saving Throw made in opposition to any effect that would limit your movement speed. Finally, if you are subject to Endurance Suppression, you only suppress half of the dice you normally would (round up).
At 4th level if you are a Tanker, or at 8th level if you are a Brute, Scrapper, or Stalker, you can use your Bonus Action to assume one of three possible Forms: Defensive Adaptation, Efficient Adaptation, or Offensive Adaptation. You can also disable your current form at any time on your Turn without costing an Action, and you will lose your current Form if you become unconscious or incapacitated. You must set aside one Endurance Die to maintain your Form. Each Form provides certain benefits.
At 7th level if you are a Tanker, or at 11th level if you're a Brute, Scrapper, or Stalker, you can use your Action to draw in genetic information from nearby creatures. Each living creature within 20 feet of you must make a successful Constitution Saving Throw or take 1d8 necrotic damage. For every two living creatures that fail their Saving Throws, you can restore one spent Endurance Die. As long as one living creature is affected, you recover a number of hit points equal to your Proficiency Modifier. A creature that fails its Saving Throw takes half damage but you receive no benefit. You cannot exceed your maximum hit points with this feature. If a dead or incapacitated creature is within the effect range of your DNA Siphon, it counts as half a creature for determining if you restore Endurance Dice or recover health.
You can use Parasitic Aura at 12th level if you are a Tanker, or at 15th level if you're a Brute, Scrapper, or Stalker.
At 10th level if you're a Tanker, or at 14th level if you are a Brute, Scrapper, or Stalker, you can use your Bonus Action to activate a sickening, disruptive aura. While this aura is active, each creature that begins its turn within 8 feet of you must make a successful Constitution Saving Throw or suffer 1d6 necrotic damage. In addition, any creature damaged by one of your targets will resist that damage. If the creature's Saving Throw is successful, it takes half damage but suffers no other effects. You must set aside one Endurance Die to keep your aura active.