If you are doing the Wave Serpent spam then there's a choice of two troop units you would consider; Guardians or Dire Avengers. You get more Guardians for more points but Avengers bring quality over quantity.
Guardians cost a cheapo 9 points a pop and are a Veteran Guardsman with WS4 and I5. They come in units of 10 base though you can take them up to units of 20.
The Guardian has the ancient doom, battle focus and fleet special rules, typical Eldar rules, really so moving on.
Wargear wise the Gurdian has a shuriken catapult which is an assault 2 bolt pistol. It is very important note that all shuriken weaponry have the bladestorm rule, which if a 6+ is rolled to wound then it auto wounds and counts as AP2. In addition they have plasma grenades which are assault grenades and can be thrown as a S4 AP4 blast.
Guardians have the option of taking a heavy weapons platform, this is basically a heavy weapon which counts as relentless. A unit with a heavy weapons platform can still embark in a vehicle, which is brilliant as you can move up, jump out and unleash bladestorm shuri catapults with your choice of heavy weapon support. You have the usual choice of shuriken cannon, scatter laser, bright lance etc though I will note that all of them are pretty expensive, the shuri cannon is the cheapest option and costs 15 points while the most expensive is the eldar missile launcher and that is double cost of the shuri cannon!
I know these are listed as a separate troop choice, but they are still Guardians at the end of the day. Basically Storm Guardians are your assault based Guardians and come armed with a shuri pistol and chainsword. More interestingly you can switch two Guardian's pistols for flamers or fusion guns (melta), which changes the Guardian's role to anti tank or anti troop.
Guardians can do two things; jump into a Wave Serpent and go full on Wave Serpent spam or bunker down on an objective with a heavy weapon platform.
If the Guardians are sitting back by your table edge then it would be wise to invest in an ADL (aegis defence line) along with a quad gun; this way you can have the Guardians putting out a high amount of medium strength shots with the quad gun and scatter laser.
The use of Guardians with Wave Serpents is pretty simple, you just roll up, bail out, unleash shuri and use battle focus to move into terrain. However, the whole point of this X vs Y article was to see if Guardians can do this better than Avengers. Time for a little bit of theory and mathshammer!
A Wave Serpent rocks up to a squad of Space Marines who are out in the open. Guardians bail out and are in 12" range with their shuri weapons. They fire 20 shots and will hit 13.2, wound 6.6 and 2.18 will be a 6+. You're looking at a total of 3.68 dead Space Marines.
This next bit is where battle focus comes into play, the Guardians can use this ability to run into cover or out of LOS. Though, LOS will be difficult as the Space Marines can easily move to draw LOS and really comes down to the type of scenery you use. If the Guardians remain the Space Marines have the option of shooting them or battering them in assault:
Space Marines fire 14 bolter shots - 9.24 hit - 6.10 wound - 4.09 dead Guardians, though this is presuming the cover is 5+.
If Space Marines fire 7 bolt pistols - 4.62 hit - 3.05 wound - 2.04 dead Guardians, again presuming 5+ cover.
The Space Marines would then assault, which the Guardians would overwatch with 18 shuri catapults and will hit with 2.88 - wound 1.44 - 0.49 dead Space Marine.
In combat the Guardians would strike first with 8 attacks - hit 4 - wound 1.36 - 0.46 dead Space Marine.
Marines return the blow with 9 attacks (inc Sgt) - hit with 4.5 - wound 2.97 - 1.99 dead Guardians.
At this point the Guardians numbers have been almost halved, which is the same result from shooting. As the Guardians are leadership 8 chances are they would fail morale and fall back. If they do not fail morale then they would probably lose combat again as one Guardian would probably snuff it.
There's also two very big important factors that need to be considered when doing Guardian Serpent spam.
As the range of the catapults is short this means bringing the Wave Serpent forward and putting it in harms way. As a Wave Serpent has excellent range there is no need for it to get up close and personal. With the Serpent close it means other enemy supporting units could return fire on the Serpent or the Space Marines could multi assault it and the Guardians, you never know may get lucky and take it out with krak grenades.
The other issue is the Guardian's 5+ armour save and battle focus, what if you do not make it into terrain? If you didn't then bolters would kill 6.10 in a heart beat when rapid firing . Even with good battle focus rolls the Guardians still could not escape return shooting or assault from the Space Marines. The only way to avoid this is to move them out of LOS like behind a ruin with no windows or something - remember you cannot assault something you cannot see!
I know Warlocks are not part of the Guardian units as standard, but they can be as they are a HQ choice which doesn't take a FOC slot and can be split off like Necron Royal Court. The Warlock is a 35 point psyker Guardian who can boost the units survival. The conceal/reveal power is very nice as a unit of Guardians sitting in a ruin on an objective could get a 2+ cover save. Protect/jinx is nice as can turn that poor 5+ armour save into 4+ or make terminator armour become 3+ and let the bladestorm commence!
The Dire Avengers are the only aspect in troop form. Their profile is almost the same as Guardians except they have leadership 9 and a 4+ armour save. They come in a unit of 5 minimum and you can boost them to 10 strong, they cost 13 points per model, which is a significant cost over the Guardian.
Avengers get the usual Eldar rule i.e battle focus etc though for some reason they get counter-attack. It is a bit weird a shooting unit gets this ability, but I am not going to complain.
Wargear, they have plasma grenades and the avenger shuriken catapult - this is basically the same as the guardian one but has 18" range.
The squad can take an Exarch, who has access to various wargear, an item of wargear which of interest is the shimmershield which gives the Exarch and the unit a 5+ invulnerable save. The shimmershield comes with a power weapon and costs an expensive 20 points. Factor in the Exarch and you are talking 30 points in total.
Avengers do exactly the same as Guardians; camp on an objective or jump into a Wave Serpent. The bonus of the Avengers of doing the same role is they cost 25 points cheaper per unit. Sure you are getting more Guardians but when your dudes are flying about in super survivable skimmers or camping on an objective you do not want to invest points in something which will not see that much use.
As mentioned above, the purpose of this X vs Y article is to see who can do the Serpent Spam better; Guardians or Avengers. I'll put Avengers to the test using the same examples as with Guardians.
5 x Avengers will bail out a Wave Serpent and fire 10 shots - 6.6 hit - 3.3 wound (1.09 chance of AP2) - 1.84dead Space Marines
Ok, so the minimum unit of Avengers isn't impressive. A unit of 10 Avengers would have the same results as 10 Guardians. Here's a recap:
They fire 20 shots and will hit 13.2, wound 6.6 and 2.18 will be a 6+. You're looking at a total of 3.68 dead Space Marines.
But, this is the part where I think Avengers shine - 18" range. Thanks to cheeky pre-measure you can roll up, bail out unleash the pain and then using battle focus move out of the Space Marine's rapid fire range and more chances of moving out of LOS as there will be more terrain between the distance of Space Marines to Avengers. This means the Avengers will be taking limited fire power in return:
Space Marines fire 7 bolter shots - 4.62 hit - 3.05 wound - 1.55 dead Avengers.
In return the Avengers have hardly taken a dent and the Marines have been chipped away.
There's two other bonuses I like about Avengers; the Wave Serpent isn't as risk as some distance away and due to range you're not throwing your TROOP choices to the wolves. I want to make it very clear that Guardians will become suicide units as they are very weak with short range weapons and will not take punishment. You do not want your troops dying quickly as it is this what win you the game, mostly.
The Guardians while not as survivable compared to Avengers, they can offer more flexibility in the form of close combat, melta and flamer. Avengers have a single role and that is anti troop. However, for Storm Guardians to work they need a turn spent outside the Wave Serpent or move up in a foot list.
Speaking of Guardians survivability, you can take a Warlock with conceal/reveal which would make the Guardians and Warlock combined cost 5 points less than a number of 10 Dire Avengers. Of course you really need terrain to make the use of conceal, but if you play on a ruin heavy board then you're laughing with a 2+ cover save :)
Dire Avengers are more survivable than Guardians thanks to the 4+ armour save and the range of their weapons, which when combined with battle focus can put them out of harms way or they receive limit return of enemy fire. They do cost a fair bit more though I feel that cost is worth considering what you get. I know counter-attack isn't mega useful due to the range of their guns, but it is still something which can help them out.
Another bonus of the Avengers is they can do MSU a lot cheaper which means more points can be invested into other areas of your army. They can also hold objectives in your deployment zone just the same as Guardians for cheaper. If you wanted you could take an Exarch and pop the unit on the quad gun.
I think the toss up between these units is down to the player.
Do you want a flexible unit who can bust tanks with meltaguns and do you minding adding in another model/unit to make them more survivable? Keep in mind that this cost would work out more than the other unit and shrouding greatly depends on you making into some form of cover. If you are ok with this then Guardians are for you.
Or do you want a unit which is more survivable, puts out the same damage at greater range though is only focused on a single role. Keep in mind that Eldar units are very niche and only have limited roles anyway. If you are happy with this then Dire Avengers are for you.
In case you want to know, I use Dire Avengers.
What is it you prefer people? Guardians in your Wave Serpents tricked out or naked? Or do you prefer Avengers, and do you take them MSU or max them out?