When the UA released in 2019 with the Onomancy Wizard, I thought the idea of using a creature's True Name to empower your spells which target it was a really interesting and flavorful idea. Sadly, it never made it past playtesting. While I was thinking about it, the idea of using a creature's true name reminded me of invocations from the Pact of the Tome warlock, specifically Far Scribe and Gift of the Protectors, which each allow for creature's names to be written in your Book of Shadows. 

In that way, I am exploring reusing parts of the Onomancy kit as additional invocations for a Pact of the Tome Warlock. I have some of the options outline below, so let me know what you think

Note: When any invocation refers to a creature whose name is written your the Book of Shadows, your tome must contain at least one page which specifically allows for names to be written on them, such as the additional pages provided by Tome of the Namekeeper or Far Scribe invocation options. 

Fateful Naming

Prerequisite: Pact of the Tome

You can cast Bane or Bless using a warlock spell slot. You can cast each of these spells at will without expending a spell slot, provided it only targets creatures whose true names are written on a page in your Book of Shadows. 

Tome of the Namekeeper

Prerequisite: Pact of the Tome

A new page appears in your Book of Shadows whose magic can be used to extract a creature’s true name. As a bonus action while holding your Book of Shadows, you target one creature you can see within 60 feet of you. The target must make a Wisdom saving throw against your spell save DC. On a successful save, you discern that this magic failed, and you can’t use this feature on the target again. On a failed save, the target is charmed by you until the end of your next turn, and the target’s name appears written on this page, if it has one.

This page can hold a number of names equal to your proficiency bonus, and you cannot use this feature to gain more names while the page is filled. As an action by touching the page, you can magically erase a name on the page or move the name to another page in your Book of Shadows where names can be written (such as those provided by other invocations). 

Devastating Resonance

Prerequisite: 5th level, Pact of the Tome

When you cast a spell using a Warlock spell slot which targets any creatures whose true name appears in your Book of Shadows, you can use this feature to impose disadvantage on the first saving throw the target(s) makes against the spell’s effect. If such a target fails this saving throw, its name is erased from any pages it appears in your Book of Shadows. 

Punishing Resonance

Prerequisite: 5th level, Pact of the Tome

After you cast a spell using a Warlock spell slot, the first time it deals damage to a creature whose true name is written in your Book of Shadows, you can use this feature to deal additional force damage to the target. This additional damage is determined by rolling a number of d4 equal to the level of spell slot expended. After the target takes this damage, its name is erased from any page it appears in your Book of Shadows. 

Purifying Resonance

Prerequisite: 5th level, Pact of the Tome

When you cast a spell targeting a creature whose true name is written in your Book of Shadows, you learn if there are any other spells affecting the creature and what they are. As part of the same action as casting the spell, you can end one of the other spell effects acting on the target by succeeding a Charisma check with the DC equal to 10+the level of the chosen spell. 

Soul-Stealer Resonance

Prerequisite: 5th level, Pact of the Tome

 When you cast a spell using a Warlock spell slot which deals damage to a creature whose true name is written in your Book of Shadows, you can use this feature to siphon some of their life force. When you do so, you gain a pool of temporary hit points determined by rolling a number of d6 equal to the level of spell slot expended. If the number of temporary hit points gained is greater than the number of hit points the target has, you can shapechange your appearance to be like that of the targets. This does not affect any objects you are wearing or carrying and lasts until you finish a short or long rest.

 Once you use this feature, the target’s name is erased from any pages it appears in your Book of Shadows. 

 

Over 2 years late here, but I love this! Have you play tested it?

Unfortunately not. If you take the time to try it out, let me know how it goes