Answer
Well I would suggest killing Daemons from afar. An army of Dark Reapers would be good but it's against the Warhammer 40k rules... I would suggest a squad of 5 Dark Reapers, 6 Swooping Hawks, 10 Dire avengers, 10 Guardians and Bright Lance Platform, War Walker with Bright Lance and Scatter Laser, Falcon with Pulse laser and Scatter Laser, Prince Yriel, 6 Striking Scorpions and 6 Howling Banshees.
It may not seem like a very good army but the tactics are Genius! Daemons have literally no Ranged weapons except for Psychic powers where your long-ranged weapons will be really effective. The Daemons also have terrible armour saves so it'll be hard for them to survive your onslaught of firepower. The only disadvantage you have is the fact they can start anywhere on the board. That's what the Striking Scorpions and Howling Banshees are for. You start with the 2 sqauds and Prince Yriel surrounding all your Dark Reapers to protect them from close combat.
Start off with the Swooping Hawks in reserve. If you get priority then move the Scorpions and Banshees away from each other and pelt the Daemonettes with the Reapers so they don't get their Rending Close Combat attacks or armour saves! If still not dead then pelt them with fire from the Shuriken Pistols from Howling Banshees and Striking Scorpions. Then charge the two squads into the Bloodletter's ranks and they should be all dead by the end of the first round of combat. If not then sacrafice Yriel's attacks to use the Eye of Wrath to unleash a Large blast attack giving the Bloodletters no armour save. Then if they have a Soul Grinder then pelt it with your Pulse Laser and Bright Lances.
Second turn Deep stirke your Hawks and drop a large blast marker over any remaining infantry and pelt them with their Lasblasters. Give any remaining Veichles a right good pelting with your Pulse Lasers and Bright Lances. Hopefully this tactic will give the enemy a great whooping. If you need an army list against Daemons with a point limit then send me the enemy's army and I'll work a great army list out for you. Just send a message to me and remember that I only make Eldar lists!
Check out the chaos daemons codex.
Try to stay in stealth. The Tau have got some stealth of their own though, and also, don't fight them in head to head combat. As Dark Eldar, try and fight dirty.
Eldar; Use lots of Howling Banshees. Tau; Groups of Fire warriors and Commander Shadowsun Imperial guard; Keep 5 Basilisks behind the lines and keep shooting across the map.
Eldar Space Marines Imperial Guard Dark Eldar Tau Chaos Space Marines Witch Hunters Gray knights Chaos Daemons Necrons Orks Tyranids
Space marines Chaos space marines Necrons Orks Tau Space wolves Daemon hunters Chaos daemons Eldar Grey Knights Tyranids Blood Angles Dark Angles Dark Eldar
The Eldar often employ fast attack tactics.
AnswerIt depends on who you are playing against.
eldar
Dawn of War featured the Space Marine, Chaos Space Marine. Orks and Eldar Armies. Follow Up Expansions Featured the Imperial Gaurd, Tau, Necrons and Dark Eldar. Dawn of War II Features the Space Marines, Orks, Eldar and Tyrannid Armies
eldar
Eldar Ryazanov's birth name is Ryazanov, Eldar Alexandrovich.
Eldar Shengelaya's birth name is Eldar Nikolayevich Shengelaya.