What is the most number of skills a character can gain Expertise in?

Question

I was reading through the Scout's Survivalist feature and noted that it is a manner by which a character can both gain skill proficiency plus Expertise in one shot. This got me wondering how many skills I could potentially get Expertise in for a single character. There have been several questions inquiring on maximizing a character's skill and tool proficiencies, but I haven't been able to identify any question discussing maximizing a character's Expertise.

For the purpose of this question, assume the following:

• Assume the character is allowed 20 levels.
• Only the character in question should be considered (i.e. no outside help).
• No epic boons.
• Any skill, feature, or item which allows the character to double their proficiency bonus for a skill is valid, it does not need to be called 'Expertise' to qualify.
• Use of any skill, feature, or item needs to have a tangible benefit. For example, if you need to be proficient in the skill in order to get the benefit of double the proficiency bonus, then that proficiency must be gained somehow to satisfy the pre-req. This avoids issues of having more Expertise than skill proficiencies raised by this question.
• Always-on is preferable to a short-term Expertise (such as what's granted by Skill Empowerment).
• Wish may be used solely within the confines of duplicating a spell.
• Multiclassing is permissible.
• Variant humans and feats are permissible.
• Any published background is permissible (i.e. no custom backgrounds).
• Magic items are permissible of any rarity except Artifact.
• No use of downtime to gain skill proficiencies.

I will consider the best to answer to be whichever one is able to come closest to gaining Expertise in the 18 skill proficiencies in the game. In the event that multiple answers can achieve this, then Tool proficiencies will be considered.

Answer 1

You can get expertise in fourteen skills (plus one from skill empowerment), and nine tools

Classes: Rogue (Scout) 6, Bard (Lore) 10, Cleric (Knowledge) 1, Fighter (Rune Knight) 3

Use the Sailor background to get proficiency in Athletics, Perception, Navigator's Tools, and Vehicles (Water). Be a Half-Elf so you can pick up another 2 proficiencies (Acrobatics and Animal Handling) and you qualify for the Prodigy racial feat from Xanathar's.

For our 6 levels in Rogue, pick Stealth, Sleight of Hand, Persuasion, and Performance right off the bat and expertise in Acrobatics, Stealth, Sleight of Hand, and Perception. We also get proficiency in Thieves' Tools. At level 3 we choose Scout, which gives us proficiency and expertise in Nature and Survival. When you hit a feat, take Prodigy and select a tool (let's go with Woodcarver's Tools) and Deception, making that expertise at the same time. We leave Rogue with 11 skill proficiencies, 7 of which are expertise, and 4 tool proficiencies.

Our 10 levels in bard we choose Insight and a musical instrument (Pan Flute) when we join, and choose College of Lore at the same time we choose expertise in Performance and Persuasion. We also choose 3 new skill proficiencies, Intimidation, Investigation, and Religion. At our first feat in Bard we take Skill Expert, taking Medicine and making it expertise. Our second feat in bard we take Skilled, and choose 3 tool proficiencies (Potter's Tools, Weaver's Tools, Jeweler's Tools). At level 10 we take expertise in Insight and Intimidation. We leave Rogue and Bard with 16 skill proficiencies, 12 of which are expertise, and 8 tool proficiencies.

We take 1 level in Knowledge Domain Cleric, gaining Arcana and History, both with expertise. We leave Rogue, Bard, and Cleric with 18 skill proficiencies, 14 of which are expertise, and 8 tool proficiencies.

For our last 3 levels, we take Fighter, choosing Rune Knight as our Martial Archetype. At level 3 we get proficiency in Smith's Tools, and with Fire Rune you double your proficiency with every ability check using a tool (granting expertise to all your tools). We leave Rogue, Bard, Cleric, and Fighter with 18 skill proficiencies, 14 of which are expertise, and 9 tool proficiencies, all of which are expertise.

Additionally, with our Bard spellcasting, we can cast Skill Empowerment to get expertise in one of the other skills that don't have it.

Answer 2

Fifteen

With a level 17 Rogue/Cleric/Bard

Race: Half-Elf, so you can pick up another 2 proficiencies and you qualify for the Prodigy racial feat from Xanathar's

Any background that gives us two skill proficiencies

Feats:

• Prodigy (XGE) + 1 expertise in any skill and 1 additional proficiency
• Skill Expert (TCE) + 1 expertise in any skill, 1 additional proficiency and proficiency in thieves' tools

Classes:

6 levels in Rogue (scout)

This is our base class so we can pick up another four proficiencies

Don't take proficiency with thieve's tools, because we can get that from prodigy and then gain expertise on it at level 6.

+4 expertises from base class, + Nature & Survival from Scout (proficiency and expertise)

1 level in Cleric (knowledge domain)

+2 expertises, with underlying proficiency, from one of arcana, history, nature or religion

10 levels in Bard (College of Lore)

Another 4 expertises, and another three proficiencies from the subclass at level three. Plus we can cast Skill Empowerment to get another expertise.

That's 15 sources of expertise and 17 proficiencies onto which we can place them.