Howdy, I recently got back into the hobby a few years ago but had to stop due to work but after a short stint away I’m back into the hobby once again. I remember when I was a kid looking at forge world minis and I’m looking into getting a few minis ordered for my Guard army, I was curious about the rules for the death korps rules as in how to deploy or use them in games, can they be used along side a regular guard army or is there separate rules etc that must be followed. Thanks in advance
does have rules for its stuff in the forgeworld Index: Astra Militarum. They can be freely used alongside a regular guard army, and can be in a keyword: Astra Militarum detachment with other units from that codex.
However, codex Astra Militarum has several special detachment benefits for having all of your models unified under the same regiment keyword. DKOK
units don't have a Regiment keyword you can choose, so they remove that rule from your army. You can't get a benefit for being all, say, Cadian if your army includes 1 squad of DKOK
So theoretically, yes, you can use the two together in the same detachment. But practically you should design your purchases such that you have a full detachment of DKOK
to run alongside your regular guards.