Spell Thief

You use the power of others against them. These rouges focus innate magical ability to manipulate any magic they cross paths with to harness its power for their own uses. Mage slayers, failed wizards, and adventures alike are some of the folks who tend follow this archetype.

Spellcasting

When you reach 3rd level, you gain the ability to cast spells. See Spells Rules for the general rules of spellcasting and the Spells Listing for the wizard spell list.

Cantrips

You learn two other cantrips of your choice from the wizard spell list. You learn another wizard cantrip of your choice at 5th level and another at 12th level.

Spell Slots

The Spell Thief Spellcasting table shows how many spell slots you have to cast your wizard spells of 1st level and higher. To cast one of these spells, you must expend a slot of the spell’s level or higher. You regain all expended spell slots when you finish a long rest.

For example, if you know the 1st-level spell charm person and have a 1st-level and a 2nd-level spell slot available, you can cast charm person using either slot.

Spells Known of 1st-Level and Higher

You know three 1st-level wizard spells of your choice, two of which you must choose from the Transmutation, Enchantment, and Illusion spells on the wizard spell list.

The Spells Known column of the Spell Thief Spellcasting table shows when you learn more wizard spells of 1st level or higher. Each of these spells must be an Transmutation, Enchantment, or Illusion spell of your choice, and must be of a level for which you have spell slots. For instance, when you reach 5th level in this class, you can learn one new spell of 1st or 2nd level.

The spells you learn at 5th, 10th, 14th and 18th level can come from any school of magic.

Whenever you gain a level in this class, you can replace one of the wizard spells you know with another spell of your choice from the wizard spell list. The new spell must be of a level for which you have spell slots, and it must be an Transmutation, Enchantment, or Illusion spell, unless you’re replacing the spell you gained at 3rd, 8th, 14th, or 20th level from any school of magic.

Spellcasting Ability

Intelligence is your spellcasting ability for your wizard spells, since you learn your spells through dedicated study and memorization. You use your Intelligence whenever a spell refers to your spellcasting ability. In addition, you use your Intelligence modifier when setting the saving throw DC for a wizard spell you cast and when making an attack roll with one.

Spell save DC = 8 + your proficiency bonus + your Intelligence modifier

Spell attack modifier = your proficiency bonus + your Intelligence modifier

Spell Thief Spellcasting

Rogue Level	Cantrips Known	Spells Known	Spell Slots Per level
			1st	2nd	3rd	4th	5th
3rd	2	2	2	-	-	-	-
4th	2	3	3	-	-	-	-
5th	3	4	3	2	-	-	-
6th	3	5	4	2	-	-	-
7th	3	6	4	3	-	-	-
8th	3	7	4	3	-	-	-
9th	3	7	4	3	-	-	-
10th	3	8	4	3	2	-	-
11th	3	8	4	3	2	-	-
12th	4	8	4	3	3	-	-
13th	4	8	4	3	3	-	-
14th	4	9	4	3	3	1	-
15th	4	9	4	3	3	1	-
16th	4	9	4	3	3	2	-
17th	4	9	4	3	3	2	-
18th	4	9	4	3	3	2	1
19th	4	9	4	3	3	2	1
20th	4	9	4	3	3	2	2

Spell Steal

Starting at 3rd level, your innate magical abilities allows you to siphon off magical essence from your foes.

As a bonus action, when you have advantage on an attack against a creature you can steal the knowledge of a spell and how to cast it from that creature.  You can only steal a spell if the creature is able to cast spells and have seen them cast a spell.  Stealing a spell does not remove that spell from the creature's spell list or a spell slot from the creature. A stolen spell must be of a level you are able to cast.  A spell thief can choose which spell they steal, one in which they have seen the caster use, or the DM can determine the stolen spell randomly.  You can hold 1 spell using this ability is held for 10 mins or until expelled by using one of the following options.

Copy Spell
As an action, cast the spell as if you had it prepared using your spell save DC or spell attack bonus.  This ability consumes a spell slot.
Magic Armor
As a bonus action, expel one held spell to gain 1d6 temporary hit points. Increases by 1d6 per held spell spent.
Channel Energy
As a bonus action, gain 1d6 elemental damage, of the spell stolen, per spell stolen on the next weapon attack.

Magical Reflection

At 9th level, on a successful saving throw against a magical effect, you send the magic towards its source at half power.  The initial caster makes saving throw against your spell save DC as normal, but duration is halved or damage starts at half initial damage.

Greater Spell Steal

At 13th level, you can hold 3 spells from your Spell Steal ability and the spells can be held up to 1 hour or until expelled.

Siphon Spell

At 17th level, you gain the ability to magically seal the knowledge of how to cast a spell from another spell caster.  When you use your Spell Steal ability against a spell caster, they must make a save against your spell save DC.  On a failed save, they forget the spell you stole it is removed from their spell list and you add it to your known spells.  You can have up to 4 spells known in this way.