Terraria (Wiki): Starfury

The Starfury is a melee weapon that pierces enemies without consuming ammunition or mana.

The Starfury is a sword that summons an (occasional) star projectile from the sky upon the cursor’s location when swung. The star has a cooldown of 0.67s, and the projectile spawns 37.5 tiles above the player and (horizontally) up to 12.5 tiles away from the place of the cursor, opposite to the player's current direction of facing. As a result, placing the cursor at the bottom of the screen will make the star fall almost straight down, whereas placing it at the top will make its trajectory veer off at a sharp angle. The stars can penetrate walls because they fall above the cursor's current location. 

The Starfury is still more potent, despite being available earlier in the game and dealing more damage than the Light's Bane and the Blood Butcherer. A Starfury cannot autoswing. Its attack reaches three tiles in radius. At an optimal distance, the Starfury can pierce two enemies. However, multiple bodies will be damaged should they all line up for the player. It is one of the key components in crafting the Zenith.

When normally used, the Starfury will emit light, making the players see better in the dark, and the light particles' continued downward motion after colliding with blocks and moving 10-35 tiles, used to reveal caves. 

The projectile deals 1.5x (desktop) / 2x (mobile, console, old-gen consoles, 3DS) the sword's damage (37 (desktop) / 44 (mobile, console, 3DS, old-gen consoles)) base damage with no knockback. It has a single piercing capability before dissipating when it hits a second enemy.

The falling star projectile won't pass through regular platforms and Planter Boxes (desktop, mobile, and console) but will go through stairs.

The player cannot switch items, look in a different direction, or use Auto Select while the star projectile cooldown is in effect, but they can keep swinging the sword. The player will be alerted to a recharged star by a small particle effect and the sound for mana restoration. 

The star projectiles are affected by the Magma stone and the set bonus of Frost armor. As a result, they emit light even when passing through blocks, which can be used to map out solid areas.

Combat-wise, the Starfury has the fastest velocity, making it effective against waves of enemies and bosses. The Starfury can be used to strike an enemy with the blade and another enemy with the star or the same enemy twice in a single swing, with accurate aim. All Flask items will imbue their unique effects since the Starfury is a melee weapon.

The speed of the falling star will increase with melee speed-enhancing gears like the Shadow armor (3DS). 

As soon as the Starfury is acquired, it is very helpful for the entirety of the Pre-Hardmode and can continue to be helpful later in the game as an exploration tool. Use caution when using the Starfury in the Underground Jungle because it can easily break the larva in an unkept bee hive, summoning the boss Queen Bee.

The Starfury is best modified with Legendary for overall stats improvement.