It would be neat if existing drums and horns would, when interacted with, increase the odds of being selected for a purge for the next hour. Much like how the player progresses through states of drunkenness and attains a vitality, then a strength buff. Working with instruments could give the clan a “Nuisance” and “Menace” buff.
I would also like it if dishonored / desecrated versions of racial banners existed. These would burn for one hour and increase the odds of the disrespected group coming to attack you.
Since both of these objects use existing art assets, sound effects, and particle systems present in the game… it would be mostly designer work to pull it all together.