Mana

Mana is a resource used by the player when wielding Magic Weapons. The player's current and maximum Mana is shown as a vertical meter of blue stars on the right side of the screen. Mana regenerates automatically, which happens more quickly when the player stands still.

Each character starts with 20 maximum mana. Using Mana Crystals increases the player's maximum mana by 20 permanently, up to a maximum of 200 (9 Mana Crystals). Maximum mana can be further increased by certain armors, accessories, and buffs, up to a maximum of 400.

The last star on the mana bar makes a pulsing motion to make it more easily visible.

Affecting Mana
In order to use magic weapons more often, certain items can increase the maximum mana or reduce the cost of using magic weapons. Because of how mana regeneration works, these can also effectively increase the rate of mana regeneration, so long as the player takes care to stay above certain current mana thresholds.

Restoring Mana
Mana regenerates on its own when not in use, until the player's current maximum is reached.

The natural rate of regeneration is modified by whether or not the player is moving, and how much current mana a character has. This formula exists to punish reckless mana use - spend all your mana, and you will have almost no regeneration at all until you stop moving or use a potion. Conversely, when the player stands still waiting between uses of magical weapons until mana is refilled, mana recovers at its fastest possible rate. Wearing items that increase the maximum mana can thus also increase your rate of recovery, as each use of magic will still leave you with more remaining mana, and the higher multiplier.

Standing still apparently multiplies the rate at which mana regenerates, by roughly twice as much.

However, mana does not regenerate for a small period of time after any magic is expended, meaning that in order to start regenerating mana the player must stop casting spells for a short time. The regen cooldown starts the moment you stop spending mana, so casting Magic Missile and Flamelash will start the cooldown as soon as it is cast, regardless of how long the projectile is held. Setting up Star Statues on Timers can help give magic-using players much better rates of magical fire in boss-fighting or enemy-farming situations where you have the time to prepare where you are going to fight. (A Crystal Ball is also helpful in such situations.)

If a player wants to rely on magical weapons for normal exploration, they should memorize how to best recover mana, even while distracted. To make the most of mana regeneration, the player should practice understanding the timing between when they fire, and when the tone that indicates they have recovered full mana occurs, (so that they fire their next attack at exactly that moment,) and try to remain stationary during times when the mana recovery starts. Firing can be practiced in a safe location like the player's home until they are comfortable with how they regenerate.

There are also several items that can be used to regenerate mana:

Note that mana restoring effects will not exceed your maximum mana and any mana restore beyond the maximum is lost. It is thus advisable to take care when pressing the mana potion hotkey to avoid wasteful overuse of mana restoring items.

Restoration potions (which also restore health,) share an item cooldown called Potion Sickness with all other health restoring items. The cooldown is 60 seconds long and begins when the consumable item is used. During this period the player is not allowed to consume any more of those items. This prevents players from bypassing hazardous areas or enemies by constant item consumption.

Note that "pure" mana-restoration items do not have this restriction - there is even the previously mentioned Mana Flower item that allows automatic consumption of mana potions for continuous mana consumption. Players may attempt continuous fire of magical attacks if they are willing to pay the costs in terms of potions to do so. Do keep in mind that as of the 1.2.3 update, consuming a "pure" mana-restoration item will trigger the Mana Sickness debuff. While this will not prevent you from consuming more mana potions, it WILL cripple your magic damage output for a short time. So if this is your chosen method of regeneration, consider having Magic Power Potions to offset the reduction in magic damage.