The Eldar in the game of
Warhammer 40,000 are one of the more interesting races to play as, certainly as it less
common than the forces of the
Imperium such as the
Sisters of Battle,
Imperial Guard and intensely irritatingly common
Space Marines.
The Eldar have many advanced forms of weaponry, but to counter their high armour piercing values, the makers of 40k, Games Workshop, made them have a really crap range.Whilst other armies have plenty of long range artillery pieces, the Eldar are unique in the fact that only one, read it, one weapon, the Prism Cannon has a realistic range of hitting any model on the gaming table.
However, as has been said, Eldar Weaponry is for the most part, very good, apart from range. Their low ballistic skill is made up for by sheer numbers of rapid firing weapons. Even the basic trooper, a Guardian has a very good weapon, the Shuriken Catapult, easily capable of scything through the armour, game wise, of most basic troopers for other races, like the Tyranid Hormagaunts, Ork Boyz and others.
Their armour save, however, isnt really much to shout about, with the 5+ on a six-sided dice being a real bitch to prevent your Guardians being cut down in great numbers. Their main defence, however, is speed. Not in the solid form of powder, just the velocity form.
Their lightweight vehicles such as the Jetbikes, Vypers and Falcon Grav Tanks must use speed to their greatest advantage. While moving over 6" a turn, any hits scored count only as glancing hits rather than penetrating ones. Their armour might not be good, but your opponent has to hit the damn things first.
The Eldar have at their command many Aspect Warriors such as the Howling Banshees,Fire Dragons, and Warp Spiders to name a few. Each are specialised toward one role on the battlefield, the Fire Dragons for example are used primarily either as tank hunting unit (Side note: Good combo is using the limited troop carrying ability of the Falcon Grav Tank to transport them into close range, since their devastating weaponry has the reach of only about a stone's throw.) or elite hunting, and are a good choice against Space Marine Terminators.
Psykers (Wizard-type people) in the form of Farseers and Warlocks are a great addition to an army, since they can give benefits to a squad of Guardians such as Conceal, which enables the Guardian squad to have an invulnerable cover save, even if they happen to be in the middle of a plain with no cover for miles around.
To sum up, the Eldar are a fantastic race to play as, if you can do it. They are powerful, but fragile, relying on speed and not sheer weight of numbers. IF you lose more than maybe 70% of your starting force, chances are you have lost the battle.The key is to keep the army constantly moving, so that the devastating but short range weaponry a chance to reap their toll on the enemy.