
Would be satisfying if MC collected all evidence of Kanna's misdeeds, expose her as a filthy mongrel in front of the whole world while keeping a record of it, casts an anti-reincarnation spell, and send her to the guillotine.
And finally end up in hell as the lowest of the low and be unable to seduce demons in there, otherwise she might seduce some demon higher up and try to come back.
BEHEAD THE HEIDI AND TURN THE PARAMOUR INTO AN EUNUCH
GUILLOTINE HEIDI'S HEAD ON TOP OF HER NECK AND GUILLOTINE THE PARAMOUR'S OTHER HEAD