Arabelle

Portent. Glimpses of the future begin to press in on your awareness. When you finish a long rest, roll two d20s and record the numbers rolled. You can replace any attack roll, saving throw, or ability check made by you or a creature that you can see with one of these foretelling rolls. You must choose to do so before the roll, and you can replace a roll in this way only once per turn. Each foretelling roll can be used only once. When you finish a long rest, you lose any unused foretelling rolls.

Fast Kid. Arabelle is so used to operating in more than one timeline that she has learned to make better use of her time. She gets two reactions per turn.

Trap Sense.  Arabelle reflexively avoids Traps. Whenever Arabelle reflexively avoids a trap, she makes an Insight Check against the DC of spotting the trap. On a success, she is aware that she dodged a trap and can warn others about it.

Sling. Ranged Weapon Attack: +5 to hit, range 30/120 ft., one target. Hit: 7 (1d4 + 3) bludgeoning damage.

Seer's Sight. Exposure to things obscured by magic has awakened an ability to sense illusions in Arabelle. As an Action, Arabelle can focus her senses to detect any Illusions within 60' of her. If the illusion would become faint from her knowledge of its nature, it does so. Arabelle has Advantage on all Saving Throws or Investigation Checks to penetrate illusions.

Ethereal Walker. Through exposure to creatures able to enter the Ethereal Plane, Arabelle's Zarovan nature as a being with one foot in the Ethereal has begun to awaken. As an Action, Arabelle can enter the Ethereal Plane for one minute or until she ends the effect as a Bonus Action.

Scram. If Arabelle is targeted by an Attack, Spell, or would be caught in a harmful effect of any origin, she may use her Reaction to move up to her full speed without provoking opportunity attacks to get away from the danger. 

Danger Sense. Arabelle cannot be Surprised but is not aware of the impending ambush until it happens. A moment prior to an Ambush, Arabelle can recognize the danger (DC:15 Insight) and call a warning, giving the party Advantage on their Perception Check to avoid being Surprised.

Glimpse of the Future. If one of Arabelle's allies is targeted by an Attack, Spell, or will be caught in a harmful effect of any origin, she can use her Reaction to warn that creature of their incoming peril. This imposes Disadvantage on the Attack Roll, or Advantage on the Saving Throw to resist the effect.