Topaz & Numby — Honkai Star Rail Character Guide

Overview

FUA support who applies Proof of Debt for a 50% follow-up damage multiplier and summons Numby as a persistent attacking unit. Peak value in dedicated FUA teams with Feixiao or Dr. Ratio; struggles in AoE content and without follow-up teammates.

FUA hybrid support/sub-DPS who summons Numby (80 SPD independent entity) and applies Proof of Debt for a 50% separate follow-up damage multiplier on the marked enemy. Core gameplay loop: apply Proof of Debt via Skill, then generate as many ally follow-up attacks as possible to advance Numby's action forward by 50% per FUA hit. Ultimate buffs Numby into Windfall Bonanza! state for 2 enhanced attacks with +150% DMG multiplier and +25% CRIT DMG, while also expanding the Advance Forward trigger to include Basic ATKs, Skills, and Ultimates.

Key Mechanics

• Proof of Debt's 50% FUA DMG increase is a separate multiplier applied after other damage calculations, making it exceptionally potent — significantly more than a simple 50% additive DMG% buff.
• Numby's action frequency scales directly with team FUA density. Each ally follow-up attack on the Proof of Debt target advances Numby by 50%, creating a feedback loop — more FUAs mean more Numby attacks, which mean more damage and Energy.
• SP flexible: both Basic ATK (via A2) and Skill count as follow-ups and advance Numby equally. The choice between them is purely an SP/damage tradeoff, not a Numby advancement tradeoff.
• Exclusively single-target — Proof of Debt can only mark one enemy, and Numby only attacks the marked target. Effectiveness drops sharply in AoE content like Pure Fiction.
• CRIT Rate is the primary stat bottleneck because consistent crits keep Numby cycling. Without signature LC, reaching 80%+ CRIT Rate requires heavy substat investment.

Best Teams for Topaz & Numby

Follow-Up Attack Hypercarry

Topaz's core role as a FUA support alongside a premier FUA DPS. Proof of Debt's 50% follow-up damage increase is a separate multiplier applied after all other calculations, making it exceptionally potent — a single debuff that amplifies every follow-up from every ally throughout the fight. Pairs with Robin and Aventurine for maximum follow-up density and damage output. Feixiao and Dr. Ratio are the best-in-slot DPS slots, but Yunli and Clara are functional alternatives.

• S-tier: Topaz & Numby, Feixiao, Robin, Aventurine
• S-tier: Topaz & Numby, Dr. Ratio, Robin, Aventurine
• A-tier: Topaz & Numby, Feixiao, Sunday, Huohuo
• A-tier: Topaz & Numby, Dr. Ratio, Tribbie, Aventurine

Follow-Up Dual Carry

Topaz acts as a secondary DPS alongside another FUA damage dealer, sharing amplification and a single sustain slot. Proof of Debt buffs both DPS simultaneously as long as both are hitting the same target, making this composition naturally efficient. Best used when two strong FUA DPS characters are available and the second amplifier slot is contested.

• S-tier: Topaz & Numby, Feixiao, Robin, Aventurine
• A-tier: Topaz & Numby, Dr. Ratio, Robin, Aventurine

Best Teammates

DPS Partners: Feixiao (S+), Dr. Ratio (S), Yunli (A), Clara (B), Jing Yuan (B)

Amplifiers: Robin (S+), Tribbie (S), Sunday (A), Ruan Mei (B), Silver Wolf (B), Pela (B)

Sustains: Aventurine (S+), Huohuo (A), Dan Heng • Permansor Terrae (A), Fu Xuan (B), Gallagher (B), Lynx (C)

Investment Priority

1. E1 — Adds +25% CRIT DMG per stack (up to 2 stacks) to all FUA attacks on Proof of Debt target — a team-wide multiplicative buff. Primary eidolon target if chasing copies.
2. LC S1 — Signature provides CRIT Rate, 50% FUA DMG boost, and Tame debuff adding team-wide CRIT DMG. Best pulled after E0 is functional.
3. E6 — Extra Numby attack during Windfall Bonanza plus 10% Fire RES PEN — next meaningful stop after signature for dedicated Topaz investment.

Best Relics

Recommended: the-ashblazing-grand-duke with duran-dynasty-of-running-wolves

Stat targets: SPD 134, CRIT Rate 70%+, CRIT DMG 140%+, ATK 2500+

Main stats: Body: CRIT Rate / CRIT DMG · Feet: SPD / ATK% · Sphere: Fire DMG / ATK% · Rope: ATK%

Important Notes

• Exclusively single-target — effectiveness drops sharply in Pure Fiction where AoE damage determines score
• Proof of Debt randomly reassigns to a live enemy at the start of each turn if the marked target dies, which can be disruptive during multi-wave fights
• Personal damage contribution collapses without follow-up attack teammates to advance Numby frequently
• Requires 80%+ CRIT Rate for reliable Numby performance; CRIT Rate is harder to source without signature cone