Tagger

Taggers are not known for stealth.  Sometimes being concealed is too insulting.  When you do some amazing heist or assassination, sometimes letting the world know is the best way.  Tagger Rogues have developed their skills with magical inks and paints to create obscure glyphs on any surface.  They have long forgone the arts of stealth to take up showboating and gloating. 

Graffiti Artist

You magically infuse your graffiti with dormant power. As a Magic Action, you can create a graffiti glyph within a 5-foot square (it can be occupied) next to you and designate a power among these choices: Detonate, Disrupt, or Empower. You can activate the stored power at the end of your turn or on a later turn as a Bonus Action.

You can create some magical Graffiti up to several times equal to your Proficiency Bonus. You regain all uses after a Short Rest.

Detonate: The Graffiti explodes in a cloud of paint and ink,  all creatures in a 5-foot radius of the graffiti must make a DEX saving throw or take Force damage equal to your Sneak Attack dice.  On a success, they take half the damage.

Disrupt:  The Graffiti explodes in a cloud of powder and confetti,  all hostile creatures in a 5-foot radius of the graffiti must make an INT saving throw or be Blinded.  Creatures that don't rely on sight automatically succeed.

Empower: The Graffiti shimmers an empowering aura, all Allies in a 5-foot radius of the graffiti are imbued with Temporary HP equal to twice your Rogue Level.  They also gain an Advantage on their next D20 Test.

Parkour Reflexes

Your reflexes to jump, run, and scale buildings have helped you escape crimes and recently tagged places.  You gain an Advantage against DEX saving throws as long as you can see it coming.  You are also granted a Climbing Speed of 15 ft.

More Ideas

Your imagination cooked up a few more ways to use your Graffiti.  You now know 2 more options:

Capture: When you activate this Graffiti, a creature within 10 feet of the Graffiti makes a STR saving throw.  On a failure, it is restrained as chains or tendrils made of paint lash out and bind the creature.  The restrained creature can make another STR saving throw at the end of its turn to try to escape.

Rejuvenate: When you activate this Graffiti, a creature within 10 feet of it is refreshed and healed for half your Sneak Attack dice.  

Back-to-Back

Why make one square of art when you can create a line of it?!

When you create Graffiti, you can use up to your full Movement to stretch that Graffiti along your path. You can only make one choice of power for this Graffiti line, however, each 5-foot square made counts as a Graffiti Placement. Emanations are the same size but a creature can only be affected once. Likewise, Graffiti that targets a creature can only be affected once.

You can use this feature once before needing a Long Rest.

Blockbuster Finale

You pour your heart and soul into one huge Graffiti.  As an action, you spray paint everywhere in a 20-foot radius centered around you.  Choose either Devil or Angel when you create it.  This Graffiti activates at the end of your turn and affects all creatures in the area.  

Devil:  The Graffiti explodes in a 30-foot-tall and 20-foot radius cylinder, all Hostile creatures in the area must make a DEX saving throw.  On a failure, they take Force damage equal to your Sneak Attack dice and are Blinded and Restrained.  They can make a WIS saving throw at the end of their turn to end one of the conditions on a success.   On a success, they only take half the damage and are affected by either Blinded or Restrained, your choice.

Angel:  The Graffiti glows in heavenly aura.  Roll your Sneak Attack dice, all friendly creatures in the area are healed that amount.  They are also cleansed of any condition or disease afflicting them.  If they were at 0 HP and not outright dead, they also gain Temporary HP equal to half the amount healed.

You can use this feature once before needing a Long Rest.