Agrith Na-Na is a banana-based Agrith-Naar from the Shadow of the Storm quest, who you must face in the final battle in the Recipe for Disaster quest. As such, he uses magic and melee attacks. He has a good defence against magic, so it's not recommended unless you have a very good Magic level. He is weak to ranged, so Karil's armour and crossbow is recommended. Another good choice is an Archer helm, Black d'hide armour and a Crystal bow/Magic longbow with rune arrows. For Melee players, he is weak to stab attacks, so a Dragon dagger (p++) is good choice. You cannot use prayer when fighting Agrith Na-Na.
He can be fought in the Nightmare Zone after the quest is complete.