Ophydian Destroyer
Ophydian Destroyers (ophidian - pertaining to snakes) are yet another addition to the ever-growing Destroyer Cults. They are also really similar to Tyranid Raveners, with multiple arms, and serpent-like bodies, and both tunnels to surprise their targets. Clearly the C'tan or Hive Mind owes the other a lot of money. Though in truth they are based upon the original Tomb Kings unit, the Sepulchral Stalker.
Harkening back to the aesthetic of the 3rd Edition Wraiths, these homicidal maniacs opted to go the serpentine spinal cord look rather than the fancy hover tech or pointy legs. Wielding a pair of Hyperphase Reap-Blades and Threshers much like their Skorpekh brothers, but also have another set of arms wielding Flayed One-like Flensing Claws called Ophydian Claws.
Tunneling Crunch
The Ophydian Destroyers are an interesting, heavily specialized unit which is slightly difficult to wrap your head around as it's full of rules and internal interactions. Their profile from the outset is 10" movement, BS/WS 3+, S4 T4 3W Sv4+ and three whole attacks. That number however is deceptive (ready your calculators): Out of your 3 base OphDes, all of them will do 2 extra attacks with their Ophydian Claws (S4 AP-1 1d); one of them will strike 3 times with his Hyperphase Reap Blades at S6 AP-4 3d (with a 3x1/6=50% chance of making an extra attack per the weapon rules), while the other two will strike 4 times at S4 AP-3 2d (per the weapon rules).
That's a lot of numbers, but the long and short of it is that a lot of things will die considering the good strength and great AP of most of these attacks. What makes these boys even more at home in close combat is their Whipcoil Bodies rule which gives them -1 to hit in melee and being Destroyers, they reroll 1s to hit. And to make sure that they will make it to melee with what they want, they come equipped with the Tunneling Horrors ability to keep them in Deep Strike as well as a special stratagem to put them back in hyperspace once they are done butchering whatever objective holder they were tasked with eliminating.
They invite two obvious comparisons, Skorpekh Destroyers and Canoptek Wraiths. All of them have around base cost (30pt, with the Wraith at 35), all of them go in units of 3 to 6, Wraiths and OphDes are both fast attack slots while OphDes and SkorDes share the same weapon. What truly separates the Ophydian Destroyers is their single-minded focus on Deep Strike and getting into melee as fast and hard as possible so they can butcher enemies as quick as possible. Which, considering their combat prowess, is pretty quick. They're also unfortunately slightly slower than Wraiths (outside of being able to natively Deep Strike) and unfortunately both less powerful than the Skorpekhs, and less durable than both of them.
As such, just holding these bad boys in reserve, preferably close to your opponent's end of the table so they are constantly reminded of it is the best strategy. They can easily spring whenever is best and completely sweep most holding units off the table in a flurry of hyperphase chops. Nasty.