Honed Marksman

You gain two related actions, "Target" and "Fire".

Target, as as action you can choose to target one enemy with a ranged weapon in the weapons range. Once the action is taken, you cannot move, use a bonus action, talk or anything else that will interrupt your aiming of your weapon. at the start of your next turn you may take the action "Fire". If you take Acid, Bludgeoning, Force, Lightning, Piercing, Slashing or Thunder damage before your next turn, your targeting is broken and you may not use the action "Fire". If before your next turn a melee attack against you fails, but rolls within 2 of your AC, you must make a saving throw Dex 13, upon a successful save, you remain targeted, upon a failed save, you lose your target and cannot use Fire next turn, but can then make an immediate reaction of a melee attack with the ranged weapon you are using as an improvised weapon melee attack at no cost to your next turn. 

Fire, (action) (requires Target) must be taken at the start of the turn before any move, bonus action, talk or anything else that will interrupt your aiming of your weapon. When using the action Fire, treat the weapon's "long" range, as normal range, and twice it's long range as it's long range. When using Target, treat 19 and 20 rolls for simple ranged weapons as Critical; treat 18, 19 and 20 rolls when using Martial ranged weapons as critical. For the duration of Fire, when rolling attack dice, increase your attack bonus by 5 to a minimum of 10. (eg +2 becomes +10, +7 becomes +12).