Hello Mark, any cultists, guard beasts/dogs, or constructs appropriate for a 3rd Level party?

For more context, I'm designing a variety of campaign prep as I'm hoping to take over as the Club DM for my local dnd club; and am designing a dungeon which is run by Cultists who worship what is essentially a BBEG imprisoned Dragon "of the void itself". I'm just looking for any Cultist stat blocks and such that fit that theme and any stat blocks you might have for guard beasts/"dogs"(or literal guard dogs lol) or constructs.