Well, not really sure how much these challenges are lore related. Can find only this piece of info via google:
So if those 5 are made by Laz/Marco and are relatively close to lore but not related maybe something crazy like Trial of deception:
Terror Bull prince rodeo drops this ring with charm oskill only in terror(or let all classes struggle and figure out a way to get charm oskill). Use that charm skill on random terror cow and make it kill one hostile cow. Get swirlies, cube charm. Shouldn't be too hard, rather tricky. First get ring, second separate few cows, get them busy on yourself/merc/summon tanking, charm one, wait.
Gekko > ok ! Alik and ViTalik in island of sunless sea drop a treasure fragment to cube with charm on terror ? And fragment drops from boss only if you have certain amount of gold in inventory ? If possible.