A strong Melt team includes Hu Tao , Yelan, and Nod-Krai expansion Xingqiu or Ganyu , Xiangling, and Xingqiu . In the former team, the increase in HP (caused by the Hydro elemental resonance) strengthens Layla's shield as she provides Freeze and Melt to a team usually focused on Vaporize. Meanwhile, Xiangling's Skill and Burst (alongside Ganyu's) make for consistent Melt damage, whilst Layla provides additional Cryo and shield

You'll have to spend a lot of time around Takashi to get lucky because you can only open his chest once a day by collecting seashells around him. If you have unbelievable luck, then you can get this on your first try.