I only know of Dwarves from Dwarf Fortress, so of course I'll be using that for the Dwarves.
Though, the cold iron thing isn't a major thing in DF. It's a mythological thing and I borrowed some aspects from Maleficent. The horseshoe use is found in folklore. On older buildings, you'll often find horseshoes nailed up, particularly in areas with certain ethnic European populations. Back in the day, the horseshoe was used to keep away witches, Fae Folk, and other evils.
The aspects of DF I've used were the sieges (Boatmurdered dealt with sieges), Dwarven jobs and hierarchy, general city layout, and a few names.
If I
really wanted to borrow from DF, the whole place would fall to chaos and ruin and the party would be forced to flee while bodies piled up and the walls were smeared with blood and vomit.