The Two Sides Of Lolth's Coin: The Drider

The cave rolls ahead of you, endless and quiet.  Only the drip of the damp nearby and the scrape of your boots.  Then you see it; an enormous web.  Far larger than it should be.  
  Instinctually, a shiver runs up your spine, the creepy-crawling feeling trickling down your arms and filling your psyche with ghastly images.  Then the cleric drops the torch, and you are plunged into darkness.  You curse in the quiet, trying to summon another light source...
  Then you hear them.  Chittering clicks and tiny echoes.  The feeling of being watched...  With a flash, another torch is lit, just in time to illuminate the path ahead.  You see...nothing.  No foes lie in wait.  And yet, something is not right, as you hear a chorus of bow strings being pulled back.  You dare to look up.  
   Spider legs.  Elven torsos.  Longbow and sword.  You have only a moment before the first arrow enters your head...

Inspiration and Lore

Gary Gygax often had a thing for strange juxtapositions.  Take the Owlbear, for example.  A cute, cuddly bear with the face of a freaking owl.  I mean...why?  Other than the fact that it easily captures the hearts of every adventurer I play with, even as its powerful claws rend the onlookers in twain, its rhyme and reason are nestled in the grand plans of its creator.  
  However, some beasties follow a logical evolution.  If elves, then what about dark elves?  If these "Drow" exist, what do they worship and why?  How can such worship be rewarded, or scorned?  This is more the case of the tragic Drider.
  In Faerun, the mystical canonical realm of Dungeons and Dragons's published materials and adventures, the Drider is a product of chaos and evil.  Tied directly to those scorned by Lolth, the Spider Queen, a Drider is the result of a Drow insulting or betraying the deity.  Driders are cursed reminders of the power of Lolth, and are equally feared and scorned by the Drow population.

Traits and Features in 5th Edition

A Drider is a terrible juxtaposition of a Drow warrior and a giant spider, where the upper half is a humanoid elf and the lower, well, is a freaking giant spider.  Powerful and dangerous, driders are accomplished fighters that make use of their versatile movement and superior size.  Walking on walls, trapping foes, and some even casting spells, a Drider is a deadly opponent against an unsuspecting party.
  By the book, these entities enjoy only the standard boons of their elven nature, but have a pretty decent AC (19 on most).  Innate Spellcasting is helpful, and with three attacks to spare, they can cut down a Player Character pretty quickly.  In packs of 2 or more, with a Drow strike team on the ground, a tactical group of Drider can overwhelm a party from the safety of the ceiling and the distance of their longbows.  Do not underestimate them; to do so might just be the TPK you're looking for.

Drider In Io
​"The Thirteen Coins"

Lolth may be vicious to her followers, but I find it strange to think that those that displease her would be twisted into a visage that most resembles her.  In fact, I'd think such an outcome to be quite the opposite.  Would not a vicious deity bless those that most please her with the great power inherent in her favorite creatures?  To grant them but a piece of the power she knows from beyond the veil, that they may better serve her fearsome wishes in the material plane.
  It is this driving belief that created the Thirteen Coins.  Thirteen prime specimens of great Drow stock, or perhaps a few of different make, that have completed the Sins of the Spider - a grueling test of wills, might, and devastating physical and mental tasks.  Seekers of the Coin perform these tasks in pursuit of greater power, following a grand vision of the goddess, who bestows upon them more and more innate abilities - all the while twisting them further toward her ideal.
  For every Seeker, the tasks are different, but each serve the greater scheme of the master.  If they complete the Seventh Sin, Lolth may bestow upon them one of her Coins; a piece of prime power, embedded in the body of her follower.  In this way, the Coin becomes an extension of the goddess, and another form of influence she can exude upon the world.
  Coins are resilient and devastating creatures, but they are not unkillable.  If ever they are bested in battle and killed, the Coin is left behind to tempt the victors with visions and power.  Destroying such an artifact is difficult and draining.  
  Such trouble to discard such a thing.  Besides, wouldn't you rather...keep it?

See you at the table, friends.
​-Adamus