MoMo says:
Devanis was surprised by the attack (I went vs passive perception), but on the following round you are able to charge forward 40 ft and still be within range to shoot at the target (albeit at long range) with your hand crossbow. It will be at disadvantage however. You can roll the 2nd d20 if you'd like to do that! Additionally, that would mean that you are not hiding, since your action would've been to attack.
Underdark Scout, yo! ;-)
• On your first turn during combat, you gain a +10 bonus to your speed.
• If you use the attack action on that turn, you can make one additional attack.
• You gain an additional benefit on all turns after your first turn: At the end of each such turn, you can attempt to hide as a bonus action if you meet the normal requirements for hiding. Deep Stalkers often use this ability to make ranged attacks, move beyond the scope of their foes’ darkvision, and then hide.