The master archer has spent years learning how to most effectively use the longbow. While capable of wielding other weapons the ranger is adept at using his bow for offensive and defensive purposes. 

Expert Strike

A master archer can focus their magical energy into their shots. You pray over your arrows daily and sometimes you call on the powers of nature when you strike an enemy. When you hit an enemy you can expend a spell slot to do additional damage. With a first level spell slot you do an additional 2D8 force damage. You add 1D8 for any additional spell level up to a total of 5d8. Also if you attack your favored enemy you do an additional 1D8 of force damage. 

Stealth Master

You are a pro at hiding from enemies. At 7th level you gain expertise in Dexterity (Stealth) checks. You also gain the ability to hide as a bonus action. When you gain the 14th level ranger feature of Vanish, this allows you to hide with advantage as a bonus action. 

Volley of Arrows

Once per short rest you can use your action to conjure a volley of arrows. Any enemies within a 15 foot radius up to your dexterity modifier you may make a ranged attack on. You may not apply expert strike damage to these attacks. But Hunter's Mark damage would apply to it's target. 

Master of Cover

You know how to most effectively use cover. When you're in cover you move up a slot. So treat 1/2 cover as 3/4 and 3/4 as full cover. Also you're skilled at maneuvering out of the way. You may use your reaction to roll a D+10 and add your dex modifier to reduce damage dealt to you while behind cover. 

Longbow Expert

You've become attuned with your longbow. If you wield a non-magical longbow your attacks are magical and ignore resistances to non-magical damage as to you your longbow is holy and blessed.