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Me and my friend play eachother alot and he rarely wins, I think the problem may be with his list, but not knowing much about eldar I decided to post his 1500pt list here on his behalf. If it helps at all I play mech WH.
Autarch with Jump Generator, Mandiblasters, Power Weapon, Fusion gun
7 Howling Banshees and an Exarch with War shout and Trikele
5 Fire Dragons and an Exarch with Tank Hunters and Crackshot (mounted in Falcon)
Falcon with Shuriken Cannon, Holo Feild and missle launcher
17 Guardians, Starcannon Platform and a Warlock with Conceal
8 Dire Avengers and an Exarch with duel catapults and bladestorm (mounted in Waveserpent)
Wave Serpent with twin starcannons and a shuriken cannon
Wraithlord with missle launcher, shuriken cannon and wraithsword
Falcon with Shurken cannon, missle launcher and holo feild.
Minor or major changes are fine. Thanks in advance guys.
I would recommend an executioner on the Exarch instead of the Triskele. Banshees are meant to charge and with the Executioner the Exarch gets +2 strength.
D.A., go with 10 if you have them
Guardians, i wouldn't put more than 10 in a squad and upgrade the Warlock to spiritseer.
Falcon, I would put a different weapon other than the Misile Launcher. A starcannon perhaps or a Scatter Laser to get more shots
Are you sure this list is accurate? For starters he can't take a falcon as a dedicated transport, so either has two falcons under heavy or one is a wave serpent. If he's using two falcons, i'd recommend dropping one in favour of a wave serpent for one of his elite choices and boosting the numbers of that squad. Probably best to up the number of banshees so they are more survivable in combat (and drop the triskele in favour of an executioner as feen039 suggested, you should be fleeting, not shooting with banshees. Also add counter attack as under 5th ed this ability becomes much more powerful).
If the dragons are solely being used to hunt tanks, they probably don't need an exarch as 6 meltaguns should be enough to melt a tank. If you do want to keep the exarch, use the dragon breath flamer and crack shot, no need for tank hunters really. This way they can melt troops and tanks, should the need arise.
The autarch doesn't seem to be adding much to this list and may be better served being dropped in favour of a farseer with doom and fortune (I'd even consider Yriel if he wants the combat punch of an autarch).
As feen039 suggested the avengers should be 10 strong. The wave serpent should go with a better option for it's weapon (the starcannon is very overcosted for what it can do). The guardians should be either lowered to 10 (with a cheaper weapons platform like the scatter laser), or dropped in favour of another unit. Either pathfinders or even more avengers (or even bikes for taking objectives under 5th ed rules).
The wraithlord can't take three weapons selections, so either has a missile launcher and wraithsword (and two shuriken catapults) or is taking too many weapons. I'd keep the missile launcher and possibly look at adding a brightlance to it and switching to flamers for support weapons.
The falcons load out is fine as the missile launcher (when firing plasma) is defensive, so can still be fired on the move, or fired krak when stationary. Look at adding spirit stones to all vehicles though.
Hope this helps somewhat but it's purely looking at problems in the list, it might help if we knew what exactly was going wrong in the games. Eldar aren't easy to use and aren't forgiving, so a different playstyle is required and there may be units in the Eldar army that better suit his playstyle.
drop the guardians, fill out the avenger squad, change the falcon to a waveserpent and then use the extra points to buy another serpent for the banshees.
The Hand that guides.
is fine the fearless field is invaluable in 5th ed
I would only ever consider this guy if i had Spiders in the list as one bad dice roll and "pop" off to the warp he goes, I would personally run a Farseer with doom and some runes of warding instead.
arrgh dump the Triskele (they are there for combat not shooting with a S3 weapon) & get an Executioner. Also max the squad out to 10, get them a serpent (personally I would go the shuriken cannon, t-l EML with spirit stones) and spend the piddly 5pts on Acrobatic.
Ok well I would personally lose the Exarch & leave the squad at 6 normal dragons, they are a one shot weapon most of the time anyways and will take out most armour in one round of shooting with or without the points draining Exarch, I would only run him if he had a dragons breath flamer if i was making the squad duel purpose. As for the falcon it can't be a dedicated transport, is it a serpent? Or does he have 2 falcons (?) if so I would suggest dumping one of them. And it needs spirit stones as well. The Eml option is all good but if he needs to save points he should cut the shuriken cannon away as the pulse laser and plasma missiles from the EML will be a better option.
Ok with the Avatar they are not a bad idea but in my experience they work better in groups of 10 with either a shurken cannon, scatter laser or in 5th ed maybe an EML. Also I love conceal, a spear might be an idea and make him a spirit seer for the Wraithlord.
I love Dire avengers, I always have at least 2 squads in my army. They should be full strength squads, 10 men so you can maximise your bladestorm. Oh and on the serpent dump the starcannons if you can, they are ok but sooooo expensive, you could have the multipurpose eml for 5pts less and with a shuiken cannon fire both on the move (well if you are firing plasma missiles) and once more you need Spirit stones.
You can only have 2 weapon upgrades, I personally would dump the sword and go with a bright lance and EML with flamers as the secondary weapons for some anti hoard. This config excels at anti tank. And between a farseer and spirit seer shouldn't spend any time imitating a statue.
As discussed before it needs spirit stones (in fact all eldar tanks should automatically buy them)
Anyways that is my 2 cents, Eldar are not an easy race to use properly, it is all about your army working as a whole.
It isn't a bad list actually it just needs some refining and retooling. So I hope that helps out some