Fireball
Fireballs work exactly the same in Rocket Riders as they do in Missile Wars: Place the blaze spawn egg down on the ground to spawn a Fireball, and punch it to launch it in a given direction.
In general, Fireballs destroy any blocks they come into contact with (depending on the blast resistance of the material), set temporary fire wherever they land, and deal damage and knockback to enemy players they hit.
Use Cases
Their most destructive use is being launched directly at TNT (as well as End Crystals and the TNT Minecarts in the Duplex) to instantly explode it.
They may be launched at other blocks in a missile, such as the pistons/slime blocks in the engine, to disable that missile. Moreover, they can be launched at a base to deal slight damage to the base.
They can also be launched at Canopies to “fire-poof” the Canopy when they hit the log and set aflame any leaves they pass through. Be careful using Fireballs on top of Canopies also; you may just set your own on fire!
They can be launched at the glass pane in the center of an Obsidian Shield. If the glass pane is destroyed, this weakens the Obsidian Shield and brings it closer to fully breaking.
A quite niche final use is redirecting or launching other Fireballs (or even stationary Obsidian Shield dragon fireballs) they come into contact with.
Note that they cannot be launched directly at exposed portals to end the game (in most gamemodes, anyway) unless the Snipe Portals game rule is enabled. They also do not interact with Vortices.
Gamemode Specific Behavior
In Swap Mode, normal Fireballs become Cluster Fireballs, which create 4 duplicate Fireballs that travel in the same direction as the original Fireball once they are punched.
In Powerups Mode, Fireballs may be used to set off End Crystals.