Neither Gacha, nor kill Tusos. It is best to go to Crystal Isles to the bubbles in the snow area. With an Angler take many black pearls from the shells. It is only necessary to enter with a Basilo to clean the bubbles (in some there are no dangers) and take out the Angler. At x1 he managed to take out 4-5 bubbles 8k black pearls.