Corpsman

Corpsman are unlike other rogues, they valiantly stand at the front lines and face off against unfathomable threats. Expert duelists and acrobatics, no other rogue can hope to match a Corpsman in close quarters battle.

Berate

Starting at 3rd level, as a bonus action you can intellectually attack a creature of your choice that can hear you. If the creature can understand you, make an Intelligence or Charisma (Intimidation) check contested by a Wisdom saving throw. If you win, the creature suffers -1d4 to attack rolls and saving throws until the end of it's next turn. If a creature succeeds a saving throw against this feature it gains advantage on subsequent saving throws against this feature for 1 minute.

Backstab

Your movement speed increases by 5 ft., and by a further 5 ft. at 9th, 13th, and 17th level in this class.

When you enter melee range with a creature and you reach a position directly opposite that of your previous position (similar to the Flanking rule), you can use Backstab. Make a melee attack roll targeting the creature, on a hit you can use Sneak Attack and reroll 1s on the sneak attack's damage roll.

Backstab also triggers if you are opposite the position of an allied creature. If the DM reasons that a creature is unable to be Flanked, it cannot be targeted by Backstab.

ODM Gear

At 9th level you have learned enough to build and maintain your own set of Omnidirectional Movement Gear. As a bonus action, you can take flight until the end of your turn gaining a flying speed equal to your walking speed. If you end your turn in the air, you fall at a rate of 240 ft. per round.

You have a number of canisters equal to your proficiency bonus. Whenever you use a bonus action to use your ODM gear, you can expend one of your canisters to double your flying speed for that round. After expending a canister, any attack before the start of your next turn deals an additional 1d8 damage.

If you are reduced to 0 hit points, your ODM Gear becomes inoperable until you use an action to repair it. After completing a long rest, all of your canisters are refueled.

Inertia Cut

At 13th level, you have gained the experience necessary to truly use your momentum to your advantage. Whenever you travel in a straight line directly before making a melee attack roll, the attack's damage roll gains a number of d4s equal to every 15 ft. you travelled beforehand, capping out at 10d4 extra damage. If you miss an Inertia Cut, you roll the d4s as if you would have hit. You must make a Constitution saving throw with a DC equal to the number rolled, becoming stunned until the start of your next turn on a failed save.

Fight!

At 17th level, you have fought so hard for survival that most threats of death simply are not great enough to overpower your indomitable will. Once per long rest at any time, you can end a single effect that is affecting you. In addition, you critically succeed Death saving throws on rolls of 18 or higher.