Soul of Sight

One Twins fight does not cover the shopping list. Building everything this material feeds takes three or four trips, and that assumes you are not splitting the loot with other players. Decide early what you want out of it. A summoner going for the Optic Staff and a melee player chasing the True Night's Edge have very different budgets, and it is easy to spend the first batch on a pickaxe upgrade and then come up short for a weapon.

The Twins are usually the mechanical boss people repeat, since a long flat bridge, campfires along it and a decent ranged weapon make the rematch quick once you have won it the hard way once.

Unlike almost every other drop, these hang in the air where they spawn instead of falling. That matters more than it sounds. Fight the Twins over water, over lava or over a gap in your arena and the loot will still be sitting at eye level when the music stops.