Source: Unearthed Arcana 17 - The Ranger, Revised

Most folk descend into the depths of the Underdark only under the most pressing conditions, undertaking some desperate quest or following the promise of vast riches. All too often, evil festers beneath the earth unnoticed, and rangers of the Deep Stalker Conclave strive to uncover and defeat such threats before they can reach the surface.

Underdark Scout

At 3rd level, you master the art of the ambush. On your first turn during combat, you gain a +10 bonus to your speed, and if you use the Attack action, you can make one additional attack. You are also adept at evading creatures that rely on darkvision. Such creatures gain no benefit when attempting to detect you in dark and dim conditions. Additionally, when the DM determines if you can hide from a creature, that creature gains no benefit from its darkvision.

Deep Stalker Magic

At 3rd level, you gain darkvision out to a range of 90 feet. If you already have darkvision, you increase its range by 30 feet.

You also gain access to additional spells at 3rd, 5th, 9th, 13th, and 15th level. Once you gain a deep stalker spell, it counts as a ranger spell for you but doesn't count against the number of ranger spells you know.

Deep Stalker Spells
Ranger Level Spells
3rd Disguise Self
5th Rope Trick
9th Glyph of Warding
13th Greater Invisibility
17th Seeming

Extra Attack

Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.

Iron Mind

At 7th level, you gain proficiency in Wisdom saving throws.

Stalker's Flurry

Starting at 11th level, once on each of your turns when you miss with an attack, you can make another attack.

Stalker's Dodge

At 15th level, whenever a creature attacks you and does not have advantage, you can use your reaction to impose disadvantage on the creature's attack roll against you. You can use this feature before or after the attack roll is made, but it must be used before the outcome of the roll is determined.