Post your tips for fighting Dark Elf armies here.
Blunderbusses probably aren't a good choice against a list with little-to-no infantry. Fewer potential hits.
Against an army with lots of Fast Cavalry, I would load up on Earthshakers and Magic, and use Bolthrowers to counter the Dragon.
A Taurus Lord could also help against the Cavalry, or against Chariots if he has the Gauntlets and a Greatweapon, but make sure the Dark Elf guy isn't taking too many Reaper Bolt Throwers, or he'll be beef-kebab in no time.
If the guy is taking Reapers, bring along a unit or two of Wolf Riders, to take them down asap.
If Chariots are in the list, use either the Lord setup above, or a Hobgoblin Hero with the Gauntlets, a Greatweapon and a Wolf.
against we daruchi (yerp, i'm a dark elf player before CD's), and slighlty contradictory to revlid, a full unit of blunderbusses will wipe out about half of any dark elf unit, though probably putting the big hats in charge range.
earthshakers are effective, eliminating the main advantage of elves. speed. thngs such as bull centaurs and hobbo wolf riders can do this too, slowing down a vunerable army that needs it's speed.
lot of grenskins can also nerf the dark elf plans, who will probably tailor there army to take out elite tin cans with beards, then see a mass of greenskins, which is realy annoying and will probably be totaly unprepered
the usual bolt throwers loose some effectivenes against dark elves, as theres not often than may ranks to pierce. but at 30 points a pop, there not a big loss if they die or miss every turn. a gaurd will almost always need to be asainged to war machines, as the speed of dark riders and harpies (and the scout ability of shades) meens that unpotected war machines may as well paint kill me on them selves
Earthshakers are a mounted armies worst nightmare. For example, in a game against such a list my unit of 40 Warriors were staring down five Knights and three Chariots. They never moved and inch due to shaking. By the time I managed to charge them, they actually ran off!
Top tip: be careful of those Dark Riders. The best solution to these would be either a few Hobgoblin Bowmen or a cheap Blunderbuss unit. Both can move and shoot and you don't need many wounds to greatly effect their effectiveness.
I don't really rate DE. They can be good if magic heavy however, also their option to take a flying terror causing monster as a hero slot makes them dangerous against low Ld armies.
I would rely on earthshakers and wolfriders to slow them down, but don't count on those tricksie elves to panic as their Ld is quite high.
A good magic defense is important and you'll need to protect your warmachines somehow (some arrer boyz or nekkid hobgoblins).
A Taurus lord is risky, it could be very effective or simply become a pin cushion for repeater bolt throwers (I've never seen a Druchii army without at least 2 of 'em).
hobbo archers rock against dark riders, cheap, BS3 and bows against low T units. Two shots - 24" range means they aren't charging from out of your range, so you get at least one round plus S&S - and at 50pts if their wiped out it don't matter
Dark Elves should be one of the easier opponents for CD.
They rely heavily on manoeuvrability, so don't ba afraid to take piles of Hobgoblins and use numbers to negate this advantage.
Don't be afraid to take Hobgob bowmen and shoot his fast cav.
Don't be afraid to take a magic denying army with lots of dispel scrolls, as he will probably be relying on magic fairly heavily.
Shoot his Chariots and Knights with bolt throwers. Use the Earthshakers to negate the speed of his cold one knights, particularly if they are large enough to autobreak your units with their fear (this is a common tactic for Dark Elves).
Use your Lord on Taurus and wolf riders to kill his bolt throwers. If he has enough of them they can really hurt your CD warriors.
Bull Centaurs on the flank, along with any spare wolf riders you have.
Consider tooling up a lord to Strength 7 to autokill his chariots.
wait... wouldnt an earth shaker be good against an all shooty army?