Plane Skipper

Plane Skippers are Rogues who have unlocked the power to enter the space between planes to aid in their infiltration, combat, and maneuverability. 

Extraplanar Knowledge

Starting at 3rd level, you gain Expertise in the Arcana skill. You have advantage on any Intelligence (Arcana) check concerning the planes of existence or a resident of a plane other than the Prime Material plane.

Additionally, whenever a creature you can see within 100 feet of you teleports, you may make an Intelligence (Investigation) check contested by the creature's Charisma (Deception) check. On a success, you know the plane and location that the creature teleported to. 

Slip into the Beyond

Starting at 3rd level, you can use the bonus action granted by your Cunning Action to teleport up to an unoccupied space a number of feet away from you up to half your movement speed. At 13th level, this distance increases to a distance up to your movement speed. 

Portal Redirection

At 9th level, whenever you miss with a ranged attack roll, you can create a tiny portal to redirect that attack. Choose a creature within 30 feet of the creature you made the attack against and reroll that attack (this can target the original creature again). If the attack hits, you can add your sneak attack damage to the attack if it wasn't already added this turn. 

You can use this feature a number of times equal to your proficiency bonus, and regain all charges on a long rest. 

Ethereal Shunt

At 13th level, you have learned how to handle enemies without killing them. When you hit with an attack roll that would deal Sneak Attack damage, you can choose to send the target into the Ethereal Plane instead. The target makes a Charisma Saving throw, where the DC is equal to half the damage the attack would have dealt, rounded up. On a failure, the target is sent into Ethereal Plane for up to 10 minutes. You can choose to bring them back earlier before the effect ends. On a success, the creature is not sent to the Ethereal Plane, but does take force damage equal to half the amount of damage the attack would have dealt, rounded up. 

Mastery of the Multiverse

At 17th level, you have learned to access the Multiverse in ways that were previously only accessible to high level spellcasters. You learn the Etherealness, Teleport, and Plane Shift spells and can cast them without expending a spell slot. When you have cast a spell this way, you can't cast that spell again until you finish a long rest. 

Intelligence is your spellcasting modifier for these spells.