Well 3 STR D attacks can be quite devastating as he can cause multiple wounds with 1 attack. I believe it's something like this, when rolling to-wound:

1: No wound
2-5: Model loses D3+1 wounds
6: D6+6 wounds

Thats alot of wounds even with 3 attacks :S

My understanding is that they are wounds to a model, not to a unit. So if he only has 4 attacks he can only remove 4 models.

2 Daemon Princes should be able to kill it in 1 turn on the charge. It can't use it's shield in CC and if they Smash, they have between them 8 attacks with rerolls to armour penetration. On average this would give you 4 penetrating hits and 1 glancing. So you have 4 attempts to roll a 5+ on the damage table, and if you can do that, the knight goes down.

And even so, if I remember correctly, Knights only have a WS of 4, so with your princes WS 9, it's still far from guaranteed it will kill a prince should it survive.

Also this. Plaguebearers shouldn't have too many problems tarpitting one of those fuckers.

As midnight said, lash of submission princes (preferably with iron arm) will make short work of it. Plaguebearers would too, however unless he's barreling it into your lines it'll be hard to get them in close combat. With princes having a very high initiative, you have good odds of smashing it down once weakened. Also remember it'll be retaliating with 3 attacks hittin on 5+, so it could whiff completely.

Alternatively; ignore it. It's shooting is meaningless to you for the most part. Throw a large unit at it to buy a turn or two.

^This is the exact reason why I think the power of (CC) Strength D weapons is greatly exaggerated. Unless it has a fuckton of attacks like the Lord of Skulls it depends on the stomp attacks to get itself out of a tarpit. The Strength D weapons are designed to kill MSU which the current meta mostly consists of. It can't handle a big blob of expandable infantry.

The Knights are the least powerfull superheavies in the game and once you get over the initial "omg it's Escalation, it's OP! Nerf plx!" you'll find there's hundreds of ways to deal with them and your opponent suddenly has to try very hard to keep the bloody things alive. If you're playing Chaos I would suggest looking into the new Hellbrute formations; DSing multimelta's with the possibillity of firing twice in a turn? Yes pls!

To be honest, my main problem with the Imperial Knight, is that it is a Escalation unit, that can be used without the Escalation addition to the game. In the campaign we play, I have refued to add Escalation as I think it's ridiculous. But this one is a unit that has STR D weapons and can be brought either way, as it's beyond that addition. But enough about my opinions of the unit.

So to sum it up, the main ways to go about it would be:

1) 2-3 Deamon princes and either smash or Lash it to death.
2) Blobs of Plaguebearers who would glance it to death with Touch of Rust
3) Ally in Helbrutes via CSM and bring them in a formation to melta it.

Well at least it gives me a couple of ways to handle it. The fact that the shield doesn't work in CC is a big up on my early estimations, so it does help alot.

Thanks guys, you're awesome!

If the pure Daemon theme is your thing, then you can ally in some Oblits as they have the Daemon rule (meaning you can even hit them with the Grimoire!) and then take your Cultist 'tax' to represent the poor stupid mortals who've gone and unleashed all this hell in the first place.

MoN Oblits require S10 to insta-kill, and can at least open up with some lascannon fire, helping you to strip the shield and open up the other facings to your Flickering Fire/Lash Princes.

Well first try today - Didn't exactly go as expected.

I put a Tzeentch Daemon Prince, with armor, wings and 2 greater gifts on the table, alongside Bel'Akor.

The Daemon Prince gets toast in round 2, as he gets 9 wounds and i roll 5 2's. Allrighty then.
After that, Bel'Akor charges in wiffs 4 of his 6 attacks. Remember that he is hitting on 3's. 1 pen and 1 glance.

The Imperial Knight strikes back, hits once and rolls a 6 - So Bel'Akor is removed from play.

Good game. How swell it is that GW decided to introduce a STR D model into regular games that you cannot exclude as it doesn't require escalation.

Gah.

I think you were on the right path here, just that the dice rolls were not in your favor this game.

Still, I can imagine how frustrating it is facing a STR D weapon, even if it is a CC weapon, in a standard game.

Is ignoring it a possibility at all? Just kill off the rest of the opponent while the Knight tackles one unit at a time?

It was a 1250 point game, so it wasn't really an option - It shoots 2 bigblasts and 2 heavy stubbers per turn, so it can do considerable damage if left unchecked.

In the end it turned up a draw - But only due to me covering with my last scoring troops behind a house while he bombarded the entire country.