i was just wondering what rules if any there are for the dlc (story packs and expansions)

Hey, sorry for the delay. There currently aren't any DLC in the runs, however if you think there should be, feel free to voice your opinion!

Is that means DLC is't allowed? I found nothing about it in rules and used all DLCs except Leviathans.

DLC is now a modifier. If you want to use DLC, then ALL DLC is fair game.