Rogue - Shadewalker
Yuriko, the Tiger's Shadow, by Yongjae Choi © Wizards of the Coast LLC
The Shadewalker is a rogue at one with the darkness - able to move seamlessly through the shadow to strike unseen at their foes.
Design-Wise: The Shadewalker is a straightforward concept: a rogue that hides in the darkness, and gets supernatural abilities in shadow. Dark Stalker gives them darkvision and a decent buff to Perception checks. Shade Call is their core feature - Shadewalkers can summon pools of shadow at will, creating their own hiding spots (and enabling Sneak Attack). Shadow Strike kicks in at 9th, giving them a shadow-teleport that applies bonus damage on their next attack. Mantle of Gloom provides some useful resistances and occasional top-ups of temp hp. And Shadow's Reach at 17th lets them command tendrils of shadow which damage and terrify their foes.
This subclass is written for both 5E (2014) and the 5e++ project.
As always, you're invited to come discuss and offer feedback on Discord!