Flower of Fire

Flower of Fire is one of many unique Magic Items found throughout Terraria, and can be found in Shadow Chests in The Underworld. When cast, it launches a slow-moving fireball which is strongly affected by gravity and arcs sharply downward. The fireball will also ricochet off of solid objects up to five times, or until it hits an enemy, whichever happens first. The spell does very high damage, has a 50% chance of inflicting the On Fire! debuff, and has some moderate knockback, considering its cost in Mana. It also works very well for hitting enemies behind objects or walls. However, the fireball will disappear if it hits water, and the weapon cannot be used underwater or under lava.

Trivia

 * This item is a reference to the Super Mario Brothers franchise, in which one of the 'power-ups' includes a flower (the "Fire Flower") that allows the player to throw fireballs which behave somewhat in the same manner.