Oath of Spider's Retribution

A Paladin who takes up this Oath shares the same goal as Drezlash the Nine-Eyed Spider, which is to get rid of the vampire Strahd, as well as the dark power who grants him his powers, Vampyr. Your Radiant powers have been abandoned, in lieu of Acid damage taking their place. Smiting will deal Acid damage, and will still do extra damage against undead creatures.

Channel Divinity

When you take this oath at 3rd level, you gain the following two Channel Divinity options.

Arachnid Protection. As a bonus action, you can grant a living creature within range armor made of Drezlash's webbing using your Channel Divinity.  One creature of your choice is granted magic resistance for 1 minute.

Frightening Gaze. As an action, you can look at a group of creatures and by using your Channel Divinity, instill intense fear into them.  When you use this Channel Divinity option, you can force an amount of creatures up to your charisma modifier to make a wisdom saving throw.  On a failed save, the creature is frightened for 1 minute.  On a successful save, the creature is not frightened.

While frightened a creature has disadvantage on Ability Checks and Attack rolls while the source of its fear is within Line of Sight, and the creature can’t willingly move closer to the source of its fear.

Oath Spells

You gain oath spells at the paladin levels listed.

Oath of Spider's Retribution Spells

Aura of Perception

Starting at 7th level, you and friendly creatures within 10 feet of you are granted Devil's Sight.

At 18th level, the range of this aura increases to 30 feet.

Fiend Guardian

Beginning at 15th level, you are able to summon 1 of 2 devils (Bone Devil or Glabrezu) that are loyal to Drezlash who are instructed to do your bidding. Using your action, the devil stays with you for up to an hour or until you dismiss it. During it's time with you, the devil can't take any hostile actions against you as it is loyal to your Patron, but it doesn't have to obey your commands if it perceives them as foolish or suicidal. The devil takes its turn directly after yours. At the end of your turn, you can give the devil a command, using no action on your part, and if the devil sees it as beneficial to itself or its plans, they acts on that command. 

Once you do this you cannot do it again until after your next long rest.

Arachnid Ascension

At 20th level, as an action, you can harness the power of Drezlash to bring down your foes. For up to 1 hour, you start to turn into the Nine-Eyed Spider. Eight spider-like legs sprout from your back, you grow extra eyes (up to nine total eyes on your head), and you grow a pair of fangs if you have none already.

During the duration of the transformation you have a walking and climbing speed of 40 feet.

In addition, for the duration, you have 2 legendary resistances and resistance to nonmagical bludgeoning, piercing, and slashing damage.

Finally, when you attack during the duration, your attacks add 4d10 acid damage when they hit.

Once you use this feature, you can’t use it again until you finish a long rest.