A sidekick who becomes a Spellcaster walks the paths of magic. The sidekick might be a hedge wizard, a priest, a soothsayer, a magical performer, or a person with magic in their veins.
To gain the Spellcaster class, a creature must have at least one language in its stat block that it can speak.
A sidekick gains the following class features as it gains levels, as summarized on the Spellcaster table.
| The Spellcaster | Spell Slots per Spell Level | ||||||||
| Level | Proficiency Bonus | Features | Cantrips Known | Spells Known | 1st | 2nd | 3rd | 4th | 5th |
| 1st | +2 | Bonus Proficiencies, Spellcasting | 2 | 1 | 2 | - | - | - | - |
| 2nd | +2 | 2 | 2 | 2 | - | - | - | - | |
| 3rd | +2 | 2 | 3 | 3 | - | - | - | - | |
| 4th | +2 | Ability Score Improvement | 3 | 3 | 3 | - | - | - | - |
| 5th | +3 | 3 | 4 | 4 | 2 | - | - | - | |
| 6th | +3 | Potent Cantrips | 3 | 4 | 4 | 2 | - | - | - |
| 7th | +3 | 3 | 5 | 4 | 3 | - | - | - | |
| 8th | +3 | Ability Score Improvement | 3 | 5 | 4 | 3 | - | - | - |
| 9th | +4 | 3 | 6 | 4 | 3 | 2 | - | - | |
| 10th | +4 | 4 | 6 | 4 | 3 | 2 | - | - | |
| 11th | +4 | 4 | 7 | 4 | 3 | 3 | - | - | |
| 12th | +4 | Ability Score Improvement | 4 | 7 | 4 | 3 | 3 | - | - |
| 13th | +5 | 4 | 8 | 4 | 3 | 3 | 1 | - | |
| 14th | +5 | Empowered Spells | 4 | 8 | 4 | 3 | 3 | 1 | - |
| 15th | +5 | 4 | 9 | 4 | 3 | 3 | 2 | - | |
| 16th | +5 | Ability Score Improvement | 4 | 9 | 4 | 3 | 3 | 2 | - |
| 17th | +6 | 4 | 10 | 4 | 3 | 3 | 3 | 1 | |
| 18th | +6 | Ability Score Improvement | 4 | 10 | 4 | 3 | 3 | 3 | 1 |
| 19th | +6 | 4 | 11 | 4 | 3 | 3 | 3 | 2 | |
| 20th | +6 | Focused Casting | 4 | 11 | 4 | 3 | 3 | 3 | 2 |
1st-level Spellcaster feature
The sidekick gains proficiency in one saving throw of your choice: Wisdom, Intelligence, or Charisma.
In addition, the sidekick gains proficiency in two skills of your choice from the following list: Arcana, History, Insight, Investigation, Medicine, Performance, Persuasion, and Religion.
The sidekick gains proficiency with light armor, and if it is a humanoid or has a simple or martial weapon in its stat block, it also gains proficiency with all simple weapons.
1st-level Spellcaster feature
The sidekick gains the ability to cast spells. (If the creature already has the Spellcasting trait, this feature replaces that trait.) Choose the Spellcaster's role: Mage, Healer, or Prodigy. This choice determines the spell list and spellcasting ability used by the sidekick, as shown on the Spellcasting table.
| Role | Spell List | Ability |
| Mage | Wizard | Intelligence |
| Healer | Cleric and Druid | Wisdom |
| Prodigy | Bard and Warlock | Charisma |
Spell Slots. The Spellcaster table shows how many spell slots the sidekick has to cast its Spellcaster spells of 1st level and higher. To cast one of these spells, the sidekick must expend a slot of the spell's level or higher. The sidekick regains all expended spell slots when it finishes a long rest.
Spells Known. The sidekick knows two cantrips and one 1st-level spell of your choice from its spell list. Here are recommendations for a 1st-level spellcaster of each role:
Mage: mage hand, ray of frost, thunderwave
Healer: cure wounds, guidance, sacred flame
Prodigy: eldritch blast, healing word, light
Spellcasting Ability. The sidekick's spellcasting ability for these spells depends on the choice you made on the Spellcasting table.
The sidekick uses its spellcasting ability whenever a spell refers to that ability. In addition, it uses its spellcasting ability modifier when setting the saving throw DC for a spell it casts and when making an attack roll with one.
Spell save DC = 8 + your proficiency bonus + your spellcasting modifier
Spell attack modifier = your proficiency bonus + your spellcasting modifier
Spellcasting Focus. The sidekick can use a focus for its spells depending on the choice you made on the Spellcasting table. A Mage can use an arcane focus, a Healer can use a holy symbol, and a Prodigy can use an arcane focus or a musical instrument.
4th-level Spellcaster feature
At 4th level and again at 8th, 12th, 16th, and 18th level, the sidekick increases one ability score of your choice by 2, or the sidekick increases two ability scores of your choice by 1. The sidekick can't increase an ability score above 20 using this feature.
If your DM allows the use of feats, you may instead take a feat.
6th-level Spellcaster feature
The sidekick can add its spellcasting ability modifier to the damage it deals with any cantrip.
8th-level Spellcaster feature
At 4th level and again at 8th, 12th, 16th, and 18th level, the sidekick increases one ability score of your choice by 2, or the sidekick increases two ability scores of your choice by 1. The sidekick can't increase an ability score above 20 using this feature.
If your DM allows the use of feats, you may instead take a feat.
12th-level Spellcaster feature
At 4th level and again at 8th, 12th, 16th, and 18th level, the sidekick increases one ability score of your choice by 2, or the sidekick increases two ability scores of your choice by 1. The sidekick can't increase an ability score above 20 using this feature.
If your DM allows the use of feats, you may instead take a feat.
14th-level Spellcaster feature
Choose one school of magic. Whenever the sidekick casts a spell of that school by expending a spell slot, the sidekick can add its spellcasting ability modifier to the spell's damage roll or healing roll, if any.
16th-level Spellcaster feature
At 4th level and again at 8th, 12th, 16th, and 18th level, the sidekick increases one ability score of your choice by 2, or the sidekick increases two ability scores of your choice by 1. The sidekick can't increase an ability score above 20 using this feature.
If your DM allows the use of feats, you may instead take a feat.
18th-level Spellcaster feature
At 4th level and again at 8th, 12th, 16th, and 18th level, the sidekick increases one ability score of your choice by 2, or the sidekick increases two ability scores of your choice by 1. The sidekick can't increase an ability score above 20 using this feature.
If your DM allows the use of feats, you may instead take a feat.
20th-level Spellcaster feature
Taking damage can't break the sidekick's concentration on a spell.