Flamelash

Hold the button and the fireball trails your cursor around the screen for as long as you keep holding, right up until it burns out about a minute later. Let go while you are dragging and it flies off along the direction you were moving. Let go with the cursor sitting still and it launches straight away from you instead, which catches people out the first time. Once released it stops obeying you and hunts down whatever is nearest on its own.

Only the initial cast draws from your bar. Holding the fireball and steering it costs nothing, and your mana quietly refills the whole time you are guiding it. For a class that spends its early game rationing potions, that changes the arithmetic completely. You can open with this, walk a fireball across a room, and start the next fight full.

• It punches through one enemy and then detonates on the next thing it touches, so line up two targets rather than one wherever you can.
• The blast reaches through thin walls and closed doors. You can clear a corridor from the safe side of a wall, which is worth remembering in the dungeon.
• With room to work, one shot can hit the same enemy twice: it pierces, curls back around as it reacquires, and connects again.
• The projectile visibly swells after the first hit. That is decoration. The second hit is not worth more than the first.

Because you decide where it goes and it throws off a lot of light, it doubles as a scout. Send it down a shaft ahead of you and you get a look at what is waiting before you commit to the drop. Water and honey kill it on contact, so it is useless over a flooded cavern, but lava does not touch it and you can steer one straight through a lava lake. Standing in liquid yourself blocks the cast entirely, though at least it does not eat the mana when it refuses.

Because the released fireball chases and pierces, an enemy being flung around a teleporter loop will keep the projectile circling after it without ever letting it land the killing hit. That lets you park damage in the air and then release it all at once, usually onto a boss the moment it is summoned.

It waits in the Shadow Chests down in the underworld, or in the Obsidian Lock Boxes that come out of obsidian and hellstone crates if you would rather fish for it than make the trip. Mythical is the reforge. Pulling this instead of a straight damage weapon is a fine result at that stage, because nothing else you can hold that early delivers damage into a room you have not walked into yet.