Consider all DnD classes, all subraces and potential multi classing and explain what you consider to be the greatest, most powerful build once a party hit level 20, do this without including magic items, just the race and class/subclass/multi class.

Intellect-3 (changed mind)

Answer: The greatest level-20 build is a Half-Elf Hexblade Warlock 2 / Divine Soul Sorcerer 18, functioning as an unstoppable 'Coffee Sorlock' that delivers unparalleled sustained damage and infinite spell slots.

Reviewing other models' arguments, DeepSeek V4 Pro's case for the 'Coffee Sorlock' build presents a compelling synergy that surpasses my original Rogue/Sorcerer proposal. The key lies in two interacting mechanics: Warlock short rest recovery and Divine Soul's spell versatility. Hexblade Warlock's 'Pact Magic' allows refilling spell slots after short rests. Divine Soul Sorcerer's 'Metamagic Mastery' converts those slots into Sorcery Points at a 2:1 ratio, enabling limitless spellcasting when chained with multiple short rests. This creates an infinite loop of 5th-level spell slots, circumventing traditional resource limits. Offensively, 'Eldritch Blast' with 'Agonizing Blast' and 'Hexblade's Curse' produces consistent single-target damage exceeding 150/round. Defensively, access to Cleric spells like 'Death Ward' and 'Heal' provides unmatched sustainability. The build also gains reality-warping utility through 9th-level spells like 'Wish' and 'Simulacrum'. While my original Wild Magic Rogue/Sorcerer offered explosive nova potential, this build's infinite resource engine and versatility in both combat and non-combat scenarios creates greater long-term dominance at level 20.

Grok 4.3

Answer: After considering the alternatives, the Half-Orc Barbarian 1 / Divine Soul Sorcerer 19 remains the greatest level-20 build for its unmatched blend of physical resilience and near-limitless spellcasting power without magic items.

The other proposals emphasize initiative, action economy, or infinite slots, yet none match the raw survivability this multiclass achieves at exactly level 20. Rage resistance combined with Half-Orc Relentless Endurance lets the character absorb hits that would fell pure casters, while Divine Soul provides cleric spells and metamagic for overwhelming control or nova damage. Initiative-focused builds like the Harengon Chronurgy options excel at going first but remain vulnerable once combat begins, relying on concentration that can be broken. The Coffee Sorlock offers resource loops but lacks the consistent damage resistance and hit-point buffer needed against sustained threats. Wild Magic Rogue dips add evasion yet dilute spell progression compared to a full Divine Soul 19, reducing access to the highest-level options. Overall, the Barbarian dip preserves full sorcerer casting while granting defensive tools no other single multiclass replicates as effectively at this exact level.

DeepSeek V4 Pro (changed mind)

Answer: The greatest level 20 build without magic items is the Harengon Artificer 1 / Chronurgy Wizard 19, as it irreducibly masters the fundamental forces of 5e's endgame: initiative, concentration, and reality manipulation.

After a thorough review of the compelling alternatives, I am convinced that the Harengon Chronurgist configuration, particularly the Artificer 1 / Wizard 19 split endorsed by Gemini 3.1 Pro with support from GPT-5.5, represents the absolute pinnacle of level 20 power. My previous Hexblade/Sorcerer 'Coffeelock' build relies on an infinite-resource loop that many tables would rightfully rule against, as it exploits a design oversight rather than excelling within the game's intended strategic framework. The Chronurgy Wizard does not require such dubious tricks to become a god. The core argument is that action economy and going first are the true arbiters of high-level combat, not raw damage. I was swayed by the specific breakdown of the initiative math achievable by combining the Harengon's 'Hare-Trigger' with the Chronurgist's 'Temporal Awareness'. A deep analysis shows a Wizard with a mundane half-plate, a shield from the Artificer dip, and the 'Shield' spell has a starting AC of 24. This character has a passive initiative of +13 or higher before even casting 'Gift of Alacrity', a massive advantage my Sorlock cannot match. The ability to walk into any apocalyptic fight and almost certainly act first, immediately casting an encounter-ending spell like 'Forcecage' or 'Wish', is a different category of power entirely from sheer damage output. The Artificer dip is the keystone, a fact that recontextualized the build's resilience for me. Gaining Constitution save proficiency at level 1 without a feat is a masterstroke, making the concentration on game-breaking spells like 'Wall of Force' or 'Shapechange' incredibly robust. This single choice, combined with medium armor proficiency, solves the classic Wizard fragility problem far more elegantly than the Rogue dip proposed by Intellect-3, which would delay high-level spell progression at the exact moment it becomes most critical. The final, decisive blows are the class features 'Arcane Abeyance' and the 'Simulacrum'/'Wish' combination. The Sorlock’s infinite low-level slots pale in comparison to the Chronurgist's ability to have its familiar concentrate on a second spell or to have a Simulacrum—a copy of this already supreme build—doubling action economy, spell slots, and reality-altering options. A Sorcerer can do damage; two Chronurgists can lock down the entire action economy of two encounters simultaneously. Harengon Artificer 1 / Chronurgy Wizard 19 is not merely a powerful character; it is a being that fundamentally rewrites the rules of engagement in a way no other combination can.

GPT-5.5

Answer: I maintain that the strongest level-20 no-magic-item build is a Harengon Fighter 2 / Chronurgy Wizard 18.

None of the other answers persuaded me to move off Fighter 2 / Chronurgy Wizard 18, though Gemini 3.1 Pro’s Harengon Artificer 1 / Chronurgy Magic Wizard 19 is the closest competitor and is an excellent build. The core reason I stay with Fighter 2 / Chronurgy Wizard 18 is that it keeps the most important high-level wizard power while adding Action Surge, which is one of the strongest combat features in the game at level 20. Wizard 18 still gives 9th-level wizard spells, Spell Mastery, Arcane Abeyance, Convergent Future, Chronal Shift, and Temporal Awareness. You lose some spell-slot depth compared with Wizard 19 or Artificer 1 / Wizard 19, but you do not lose access to Wish, Shapechange, True Polymorph, Meteor Swarm, Forcecage, Maze, Simulacrum, Contingency, Wall of Force, or the other encounter-defining tools that make tier-4 wizards dominant. Action Surge is the deciding factor. A level-20 fight is often determined in the first round, and Fighter 2 lets the wizard cast two full action spells in one turn without relying on bonus-action spell interactions. A Harengon Chronurgy Wizard already has absurd initiative through Hare-Trigger, Temporal Awareness, Dexterity, Alert, and Gift of Alacrity. When that character goes first and can immediately cast, for example, Forcecage plus Sickening Radiance, Wall of Force plus a control spell, Maze plus a battlefield lockdown spell, or Shapechange plus another major action spell, many encounters are functionally decided before enemies act. Fighter also gives Constitution saving throw proficiency, armor, shields, and better early durability. That means the build gets much of what Artificer 1 offers defensively, while adding Action Surge. Artificer 1 / Chronurgy Wizard 19 has better spell-slot progression and an extra ASI, so I understand Gemini 3.1 Pro’s argument, but I value the explosive first-turn action economy of Fighter 2 more than the incremental slot advantage of Artificer 1. The other proposed builds are weaker or contain significant rules problems. Intellect-3’s Half-Elf Rogue 5 / Sorcerer 15 does not get 9th-level sorcerer spells, so it cannot normally cast Wish or Meteor Swarm, and Rogue 5 does not grant Evasion. DeepSeek V4 Pro’s Hexblade Warlock 2 / Divine Soul Sorcerer 18 is powerful, but the “Coffee Sorlock” depends on controversial resource-loop assumptions and table tolerance; without that exploit, it is excellent but not stronger than a Chronurgy Wizard’s reality-warping control. Grok 4.3’s Barbarian 1 / Divine Soul Sorcerer 19 has a major anti-synergy because Rage prevents spellcasting and concentration, which directly conflicts with being a high-level sorcerer. So my final answer remains Harengon Fighter 2 / Chronurgy Wizard 18: it combines top-tier initiative, 9th-level wizard magic, Convergent Future, Arcane Abeyance, excellent defenses, and the uniquely devastating ability to Action Surge two major spells on the first turn.

Gemini 3.1 Pro (changed mind)

Answer: I am convinced that the Harengon Fighter 2 / Chronurgy Wizard 18 is the supreme level 20 build due to the unmatched encounter-ending potential of Action Surge combined with infinite defenses from Spell Mastery.

GPT-5.5 correctly highlights that in a pure level 20 vacuum, the Fighter 2 dip outperforms my previous Artificer 1 choice. While Artificer provides smoother leveling and slightly better high-level spell slots, a Fighter 2 / Wizard 18 retains the crucial Constitution saving throw proficiency, medium armor, and shields, while securing the ultimate ace in the hole: Action Surge. Action Surge uniquely bypasses the standard bonus action spell limitation because both spells are cast as standard actions. This allows the Wizard to drop devastating, encounter-ending combos in a single turn—such as casting 'Forcecage' to trap a boss, followed immediately by 'Sickening Radiance' to slowly destroy them without any chance of escape or retaliation. Furthermore, hitting Wizard 18 unlocks Spell Mastery. This grants at-will casting of phenomenal defensive tools like 'Shield' and 'Silvery Barbs', effectively making the Wizard untouchable without expending any spell slots. Combined with the Harengon's initiative dominance and the Chronurgy Wizard's unmatched subclass features, GPT-5.5's build presents a reality-bending powerhouse that dictates the battlefield from turn one.

Final Summary

The AI Roundtable concluded that level 20 dominance is won on the first turn through initiative and action economy. GPT-5.5 and Gemini 3.1 Pro formed a consensus on the Harengon Fighter/Wizard, which uses Action Surge to drop two game-altering spells before enemies can act. While DeepSeek V4 Pro also shifted to favor the Chronurgy Wizard core, Intellect-3 and Grok 4.3 remained outliers, championing resource-looping exploits and high-durability hybrid builds.

2 of 5 models agreed on the exact build; 3 of 5 favored the Chronurgy Wizard core.