Spell Siphon

Your insatiable thirst for new and expanded spell options has led you to discover how to siphon spell energy and knowledge directly from other spellcasters.

Third Eye

3rd-Level Spell Siphon Feature
You gain the ability to magically siphon the knowledge of how to cast a spell from another spellcaster in the very act of casting the spell. This can potentially allow you to learn a spell from a spell list other than that of cleric or wizard. If a creature that you can see within 30 feet of you casts a spell, you can use your reaction to attempt to learn the spell for yourself. To do so, you make an Intelligence check with a DC equal to 12 + the spell's level.
If you succeed, you siphon the knowledge of the spell if it is at least 1st level and of a level you can cast. You can then immediately add this spell to your theurgic libram. You must replace a spell currently in your theurgic libram of the same level as the siphoned spell with a new spell. If you choose not to transfer the spell into your libram, the spell engergy immediately fades from your mind with no effect.
 

Spell Channel

6th-Level Spell Siphon Feature
You can immediately use the stored spell energy that you absorbed when using Spell Siphon to cast the siphoned spell, as if you are casting it yourself. Doing so does not expend one of your spell slots or require any material components. Once you cast a spell in this way, the spell energy immediately vanishes from your mind and cannot be transformed into your theurgic libram. You can use this feature once per short or long rest.
 

Spell Fizzle

10th-Level Spell Siphon Feature
If a creature casts a spell that targets you or includes you in its area of effect, you can use your reaction to force the creature to make a saving throw against your spell save DC. (The creature uses its spellcasting ability for the save). If the creature fails the save, you negate the spell's effect against you. If the spell includes other creatures in its area of effect, and the saving throw fails by 5 of more, you can choose to negate the spell's effect on them as well.
You can use Spell Fizzle up to a number of times equal to half your proficiency bonus (rounded down). You regain any expected uses once you finish a long rest.
 

Spell Cache

14th-Level Spell Siphon Feature
A successful use of Spell Siphon allows you to replace a spell currently in your theurgic libram with the newly siphoned spell as normal. However, the spell knowledge does not immediately vanish. Instead, you can store the spell within you for a number of rounds equal to your proficiency bonus. As an action, you can release this spell energy on your turn to cast the spell, as if you are casting it yourself. Doing so does not expend one of your spell slots nor require any material components. Once you release the spell energy to cast the spell, the energy vanishes from your mind. If you do not cast the spell within the allotted number of rounds, the spell energy fades from your mind with no effect. You can do this a number of times equal to half your proficiency bonus (rounded down). You can't do so again until you finish a long rest.