Shadowflame Knife

Each swing sends a knife flying flat for a moment before gravity takes hold, so at range you aim above the target. The knives bounce off enemies rather than passing through them, so a tight cluster can pass one back and forth a couple of times, but any block ends the projectile instantly. Open air suits it far better than a tunnel does.

A Goblin Army can be summoned the moment you break into Hardmode, which puts this in your hands before any mechanical boss and keeps it relevant well past them. Shadowflame is the real draw, since the burn ticks on top of every hit and the bouncing keeps finding fresh segments of The Destroyer. One thing to plan around: melee speed bonuses make the knives fly faster but do not make you throw them any quicker.

The Magic Dagger is the obvious comparison. It throws faster and pierces, so it is the better crowd tool, but it costs mana and reaches less far. On a single target the two land close enough that the burn decides it, unless the enemy shrugs off Shadowflame.