Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

I will make it quick:

Can you take allies in a game of 40k (like units from another army) and if so what are the rules?

See codex witch hunters or codex Daemonhunters

Only Imperial armies can officially ally with another core army anymore.

Space Marines and Imperial Guardsmen may ally with Inquisitors, Daemonhunters, and Witch Hunters.

May i take this chance to ask if IG can ally with SM?

IG and SM can't ally, not even through DH or WH.

But arent SM supposed to come in and "clean up" things IG can't handle? GW confuses me :(

You're confusing fluff with rules.

Consider that these are fairly small engagements in 40k. Roughly company-size. The scale of the battle isn't big enough to encompass the marines coming in to bail out the guard.

And you can field SM and IG together - in Apocalypse. Which, is a much larger scale battle. You could build a 1500 point Marine and 1500 point IG list and you'd be set for APOC. Actually, you could throw in a 500pt Baneblade, and then only need 2500 pts combined of IG and SM.

Don't tell me. You haven't played since 2nd ed?

Only DH and WH armies can be "allied" with these days. These codices list what units can and cannot be used and in what order.

e.g. Using a Daemon Hunters (ordo malleus) army as your main army. If you have Grey Knights in your army, you may not take SM forces as allies. You may take IG or WH units.
However, if your main army is Space Marines, then you are allowed to take Grey Knight units as allies. Confusing? You betcha.

With Witchhunters (ordo hereticus) army, if you take Sisters of Battle, you may not take SM as allies (but you can take Grey Knights), but once again, if playing as SM, you may take SoB allies (or GK).

Now i see how a noob like me can get confused thx

Even more confusing:
If you look at the DH codex, you can find the rules chromedog quoted, meaning: DH may use certain SM units as allies, unless they use Grey Knights. They also may use certain IG units.

Yet if you take a look at the WH codex, besides rules explaining what WH may take as allies, you also find that DH may take WH as allies:

"Witch Hunter units can be included as allies in the following codex armies:
* [SM and loyalist variants]
* [IG and variants]
* DH (!)

Although the last one is not stated in the DH codex. I figure, the WH codex was written afterwards (well, better than never, Ordo Xenos anyone?).

Great! More anti-tank for DH! Better cheap capturing troops choices!

Uh, perhaps you should either get the second printing of Codex Daemonhunters or else check the FAQ.

You referring to my last post with yours, Ghaz? Because in that case I am not sure what exactly you mean - it would have been rather helpful if you had continued your one-liner with "...because there you would find that...".

The FAQ has a section about allies, that's true. But none refers to the idea of DH taking WH allies:
* The first says that armies that have WH or DH allies may not take any other allies.
* The second says "Sisters of Battle" means WH
* The third says armies using DH allies may also take WH allies
* The fourth says that a DH death-cult assassin may only be taken if you have a DH inquisitor.

There is also a paragraph stating that DH may not use "detachments" that use other allies and gives Kroot mercenaries as an example. Which to me indicates that the authors want to keep it "in the family", meaning the Imperium.

So, after reading the FAQ: What does the second printing of the Codex DH state on this issue?

The fact that Daemonhunters have always been able to take Witch Hunters as allies and vice versa. As per the FAQ you yourself just quoted the term 'Sisters of Battle' means 'Witch Hunters'. Bothe codices are worded the same in this regards, so what's confusing in the one and not the other?

Tau can take alien allies like kroot and vespid

Please don't try and confuse the original poster. Kroot and vespid are not 'allies', but a part of the Tau Empire army list.