Bloodbeard:
For advice and tactics when fighting Daemons of Chaos using the LoA list.
sam585:
Demons of Nurgle are very tough and resilent. The entire army has high toughness, and rely on mainly poison to do meaningful damage in close combat (not including the greater demon who is very strong). Thus most battles become wars of attrition, and they will win that war if we do not support our units properly either with shooting, magic, or combo charges.
Lore of death, purple sun will demolish this army but flames of azgorh and ashstorm will be just as effective.
The Taur’ruk with the OTS and a 1+ rerollable is a good choice for combating this army making them reroll there demon saves, and bringing another source of str7 for mulching the demon specials and rares in close combat.
You need khans against this army. NEED.
Infernal Guard with shields or blunderbuss are a very good choice against this army since we retain our very good armor save and parry making it harder for them to poison us.
Magma cannons are likely mandatory due to the beasts of nurgle, and large infantry block, try to take 2 then whatever other shooting you wish.
Centaurs are not a bad choice since they are great in a grind, but hit harder, with higher ws then the average nurgle demon, and a good armor save. Give them the banner of eternal flame to lower there chances of getting road blocked by beasts of nurgle.
K’daii destroyers are not too bad in this matchup, but need to be used carefully since the entire army has access to poison attacks. Never send him in alone.
Typical lists will include:
Greater Demon of Nurgle
Herald+ large block of plague bearers
Beasts of Nurgle. Atleast 2 units, likely 3
If really competitive, I would expect to see some furies for more chaff
Plague Drones (two units of 3 or one unit of 5)
If competitive 2 Skull cannons if not, expect to see the weaker defiler monster.
The Greater Demon of Nurgle is a serious monstrosity, with good WS, mark of Nurgle, high toughness, high wounds, high attacks, basically a very strong combat monster. We do not want to tackle this thing in close combat unless it is already weakened. It is toughness 7, so our rockets fail to wound on a 1 and 2 which makes taking him out with machines a little tougher. He is slow tho, and easy to block with chaff, we will need to do this because we don’t want this thing anywhere near us when it has full wounds or supporting combat units.
Herald(s)+ large block of plague bearers
This unit will usually be pretty large (35-40) due to them not having many other choices when going for a mono theme. The plaguebearers by themselves have low damage output outside of poison, but are very effective during the grind, much like infernal guard. The Herald(s) however will usually be in this block giving the unit some much needed combat punch making them much more dangerous. Though much like the greater demon, they are quite slow and we will get several rounds of shooting against them. Magma cannons are perfect at thinning this unit out, and we will need to to make the unit manageable in close combat. Once combat starts, we need to direct as many attacks as possible to the heralds due to how much they augment the unit, with only 2 wounds it should not be too difficult to cut them down.
Beasts of Nurgle.
These things are very nasty. Expect to see between 2 and 3 units of these one/two being small and one being largish. They have a pretty fast movement, do d6+1 attacks a turn, have poison, regeneration, and toughness 5. They are very difficult to kill in close combat, and will bog down whatever unit we send into them. The K’daii destroyer will be ok against a unit no bigger than 3, anything else and he risks getting beaten up and dying. Centaurs in a combat block 5-6+Taur’ruk with flaming banner, or warbanner, can grind out this unit, but still the same issue of being stuck fighting these things for a few rounds. Infernal Guard block with shields have a decent chance at beating these units too through static combat res, and having good armor and a parry.
Plague Drones
These guys are pretty strong, and don’t let the skirmishing fool you. The mounts have 3 attacks each, strength 5, poison, with a str 5 stomp and toughness 5. The rider is a normal plaguebearer. They are fast with the 3d6 flying charge so have a big threat range. A unit of 3 is more of a support unit for the larger blocks, or Beasts of Nurgle. But a bigger block of 5 will cause a lot of damage to our RnF, and pack enough attacks to get a decent amount of poision damage through every round against us. If they hit us on a flank, prepare for sad times.
Skullcannons, these things are a big threat to our warmachines as are any cannon, but against out Destroyer, and RnF its not too bad due to it having flaming shots. It does have a 5+ wardsave like any other demon and a decent amount of wounds.
The big defiler monster, is really not that scary compared to the rest of the army. They are pretty redundant in a mono-nurgle list. They have a really low amount of attacks, and are mainly relying on thunderstomps in close combat to win. So plan on beating it with static res, a Taur’ruk with OTS, or the K’daii.
Furies are flying chaff. Not that strong, and can be dealt with by sending in an armored khan with spear.
TheHoodedMan:
sam585 pointed out a lot of good things:
From my side to add: With a great weapon BSB in a handweapon/shield IG block there is a decent chance to beat a nurgle beast unit (stay deep ranked + 2 standards for high combat resolution). With a flame banner this is even a little better.
Plague bearers: For decimating these (and nurgle beasts, plague drones as well) a magma cannon is very nice, but the bearers can well be hit with a death shrieker as well. You have to hit these bearers early because if they get a combined combat with a demon in full number they nullify our advantage in static combat resolution and they can grind down a IG unit in few rounds.
The death shriekers are also very useful against the cannon and the new greater demons of Khorne (which I saw lately at two tournaments).
If you play an Iron Demon try to use him for shooting because of the poison attacks of the nurgle demons. Cannon and all multi wound demons are rewarding targets.
MadHatter:
I’d go dual hellcannons and dual magma, you need the hellcannons on the flanks of your magmacannons to defend against ambushes and cavalry. Hellcannons try to wreck the guo, magmacannons weaken the plaguebearers. Smash a baletaurus into the plaguedrones and keep guo or plaguebearer block ashstormed 
Bale breath goes over the plaguebearer block if possible
No arcane armor or talismans for daemons so no dispel scroll or firegem/helm in the daemons army
Watch out for the d3 wounds on the nurgle heralds balesword, lost my sorc.prop. to a poison 6, failed wardsave and 3 wounds
Best of luck! :hat off