Hello! I apologize if this has been suggested before, I have seen some periphery suggestions about moulder but none like this.
Also, in advance, I acknowledge that most of this game's DLC is already in the works/already made and awaiting release. This is mostly just for fun.
Clan Moulder is, as you all know, known for insanely twisted beings that are created from bought/kidnapped members of various races. It is also known for a few specific specimens, one of which is Ghoritch, a rat ogre with the mind of a Norscan warrior. This brain gives Ghoritch unnatural intellect for a rat ogre, and he rose through the ranks of Clan moulder's faction.
I propose using him as a skaven horde faction. The skaven suit hordes and it puzzled me that no base game skaven had this as a mechanic. Ghoritch would behave much like any other raid faction, but with support from Moulder (No, none of that horrible "Nakai defense of settlements you cant use" crap. A full fledged faction that acts as a vassal but still can make and build armies and do it's own thing.) The twist is that to get new units, ghoritch must capture enemies by defeating armies or a special option similar to sacking settlements, but with kidnapping. These units would vary and be based on the faction they were stolen from. This would create a "Seek and aquire" horde faction that requires a bit more thought and shopping-list style planning to unlock units and abilities. Similar to Ikit's workshop, there would also be upgrades you could spend these races on to improve your units. So in total, you need to capture units to unlock a unit, then more captures can either reduce the recruitment time/cost or be used for research. Throt could potentially be used as a legendary lord for Ghoritch (I know he would be a better symbol for moulder than Ghoritch, but he is a scientist who remains at the hellpit in lore, not a conqueror) or might lead clan moulder's forces seperately from the player. Also, for petes sake, let Ghoritch control the garrison battles and units in Moulder's armies when they fight to prevent the "Nakai's garrisons get wiped for being useless" frustration.
Again, this is mostly just for fun. Thanks for reading!