Frtiz here from Way of Saim-Hann. When was the last time you saw a Vyper on the table? If you play Eldar why are there no Vypers in your list?
"Fritz, they are open topped, AV 10, and have expensive weapon upgrades- plus they work in squadrons which is the kiss of death in 40K. Besides everybody knows war walkers are superior for the points… "
Well it is these points that I want to refute and to at least convince my fellow craftworld brothers why there should be a few Vypers in the warhost. Mon-keigh, beware if you see them on the table when combined with some tactical knowledge!
The key to using Vypers is to combine their speed as fast skimmers and range with the correct weapons loadout into a supporting role for the rest of your units. If your Vypers are on the front line getting rapid fired to death that squadron is going to go down that turn. Let’s start with the weapon loadout first.
Arming the Vyper
The Vyper has a back mounted turret which can be either a star cannon, brightlance, shuriken cannon, EML, or scatter laser. By default it also comes with a twin linked shuriken catapult on the underside which can be upgraded to a shuriken cannon.
Unless you are filling a specific gap in your army the scatter laser is the best choice for the vyper turret. Four shots make up for hitting on a 4+ and S6 has some decent hitting power against a variety of targets- infantry, monstrous creatures, and light armor. Second to the scatter laser is the star cannon. Even though its pricy and only kicks out 2 shots, the fact is that the majority of people play space marines. Star cannons make space marines cry when your frag them out in the open with no cover saves around.
As for the other two: the shuriken cannon only has a 24” range, we want that 36”, and brightlances are beyond expensive for a single S:8 shot even with the lance ability. There are better Eldar anti-tank options.
The missile launcher kind of falls in the middle with the single shot or template, but neither option is really that good. A single shot can miss, and a frag grenade template really isn’t killing that much if it finds its mark.
Regardless of your turret, you want to also go with the under slung shuriken cannon upgrade for more firepower and something else to pop off if you get hit with a weapon destroyed. Keeping it a shuriken catapult means you have to be 12” away from your target, and this is bad…
Using the Vyper
So, lets look at a squadron of three Vypers with scatter lasers and shuriken cannons = 16 S6 shots at 36” and 12 S6 shots at 24”. Mobility and range is the key to using these shots. With the range and ability to move 12” and fire at 36” engaging vehicles on side armor vypers have some nice anti-armor punch. Often I’ll use one group to crack open a transport and the other to gun down the dudes inside. Guys laugh when I say S:6 shreds armor, thinking everything in 40K is always striking the front armor. Side and even rear shots become the norm with the Vyper's mobility. Vypers also work as supporting wolf-pack units. Soften up an infantry unit at range and then send in the jetbikes to finish the job.

Which detours out over to war walkers for a moment. Cheaper, more shots, and not open topped war walkers are more or less a static unit. Sure they can outflank, but once they enter the game they can’t redeploy like vypers can. Less shots with the ability to be almost anywhere on the table next turn is huge! Being AV 10 war walkers are still vulnerable to everything but a grott so they need cover. Vypers can create their own cover which brings us to the squadron issue.
If half the unit is in cover you get cover saves to negate incoming shots. Vehicles fire from the gun/turret and the top turret peeks nicely over wave serpents and fire prisms. If you can’t use terrain to collect a cover save, park that energy field Wave Serpent in front of the Vyper squadron. Often I’ll have a wave serpent move fast right up to my vypers so it collects the cover saves. Vypers fire away, and then the wave serpent star engines right in front of the Vypers for cover saves all around.
~There are lots of other little tricks that open up with Vypers like using them to contest objectives since they can fly over models, building skimmer walls, and boxing in land raiders so they can’t move or escape out with the skimmer ram rule, but I can’t give everything away to the Mon-keigh on this blog…