Characters of spellcasting classes can cast a number of spells each day; the spells you can cast in a day are referred to as spell slots. At 1st level, a character has only a small number of 1st-rank spell slots per day, but as you advance in level, you gain more spell slots of higher rank. A spell’s rank indicates its overall power, from 1 to 10.

Prepared Spells

If you’re a prepared spellcaster—such as a cleric, druid, witch, or wizard—you must spend time each day preparing spells for that day. At the start of your daily preparations, you select a number of spells of different spell ranks, determined by your character level and class. Your spells remain prepared until you cast them or until you prepare spells again.

Each prepared spell is expended after a single casting, so if you want to cast a particular spell more than once in a day, you need to prepare that spell multiple times. The exception to this rule is for spells with the cantrip trait; once you prepare a cantrip, you can cast it as many times as you want until the next time you prepare spells.

You might gain an ability that allows you to swap prepared spells or perform other aspects of preparing spells at different times throughout the day, but only your daily preparation counts for the purpose of effects that last until the next time you prepare spells.

Spontaneous Spells

If you’re a spontaneous spellcaster—such as a bard—you choose which spell from your spell repertoire that you’re using a spell slot for at the moment you decide to cast it. This provides you with more freedom in your spellcasting, but you have fewer spells in your spell repertoire, as determined by your character level and class. When you make your daily preparations, all your spell slots are refreshed, but you don’t get to change the spells in your repertoire.

Heightened Spells

Both prepared and spontaneous spellcasters can cast a spell at a higher spell rank than that listed for the spell. This is called heightening the spell. A prepared spellcaster can heighten a spell by preparing it in a higher-rank slot than its normal spell rank, while a spontaneous spellcaster can heighten a spell by casting it using a higher-rank spell slot, so long as they know the spell at that rank (see Heightened Spontaneous Spells below). When you heighten your spell, the spell’s rank increases to match the higher rank of the spell slot you’ve prepared it in or used to cast it. This is useful for any spell, because some effects, such as counteracting, depend on the spell’s rank.

In addition, many spells have additional specific benefits when they are heightened, such as increased damage. These extra benefits are described at the end of the spell’s stat block. Some heightened entries specify one or more ranks at which the spell must be prepared or cast to gain these extra advantages. Each of these heightened entries states specifically which aspects of the spell change at the given rank. Read the heightened entry only for the spell rank you’re using or preparing; if its benefits are meant to include any of the effects of a lower-rank heightened entry, those benefits will be included in the entry.

Other heightened entries give a number after a plus sign, indicating that heightening grants extra advantages over multiple ranks. The listed effect applies for every increment of ranks by which the spell is heightened above its lowest spell rank, and the benefit is cumulative. For example, fireball says “Heightened (+1) The damage increases by 2d6.” Because fireball deals 6d6 fire damage at 3rd rank, a 4th-rank fireball would deal 8d6 fire damage, a 5th-rank spell would deal 10d6 fire damage, and so on.

Heightened Spontaneous Spells

If you’re a spontaneous spellcaster, you must know a spell at the specific rank that you want to cast it in order to heighten it. You can add a spell to your spell repertoire at more than a single rank so that you have more options when casting it. For example, if you added fireball to your repertoire as a 3rd-rank spell and again as a 5th-rank spell, you could cast it as a 3rd-rank or a 5th-rank spell; however, you couldn’t cast it as a 4th-rank spell.

Many spontaneous spellcasting classes provide abilities like the signature spells class feature, which allows you to cast a limited number of spells as heightened versions even if you know the spell at only a single rank.

As a spontaneous caster, you can also choose to cast a lower-rank spell using a higher-rank spell slot without heightening it or knowing it at a higher rank. This casts the spell at the rank you know the spell, not the rank of the higher slot. The spell doesn’t have any heightened effects, so it’s usually not a very efficient use of your magic outside of highly specific circumstances. For instance, if your party was having trouble with an invisible enemy, and you had revealing light in your repertoire but had already spent all of your 2nd-rank spell slots, it might be worth it to use a 3rd-rank spell slot to cast the spell, even though it’d have no heightened benefit.