DMG Bonus & Vulnerability

“More damage” can mean two different things

An effect that increases an attacker’s damage dealt and one that increases the target’s damage received can both make a hit larger. In ordinary direct-damage calculations, applicable DMG Bonus and vulnerability belong to separate multiplier families.

This distinction explains why adding 20 percentage points to an existing bonus need not produce the same result as adding a new 20% damage-taken effect. Start by reading what the effect modifies, then check which damage it covers.

The examples below isolate these two families for an ordinary direct hit. They do not calculate a full Character rotation or establish how every special damage source works.

Add only the DMG Bonuses the hit qualifies for

A relevant Elemental DMG Bonus, a general DMG Bonus and an applicable attack-type bonus contribute to the ordinary DMG Bonus total. They do not become separate multipliers just because one came from a Relic and another from a support.

Suppose a direct Fire follow-up hit has 20% Fire DMG Bonus, 10% general DMG Bonus and 10% follow-up DMG Bonus. All three apply, giving 40% in this family and a multiplier of 1.4. An Ultimate-only bonus would not join that total unless the damage also qualifies as Ultimate damage.

The wording and attack classification decide eligibility. A bonus to an Element does not turn an attack into that Element, and a Skill button does not by itself settle every damage label. The Follow-up Attacks and Counters guide explains why those labels matter.

Vulnerability amplifies qualifying damage received

Vulnerability is the common mechanics term for increased damage taken or received. It can be broad or restricted to a particular Element or damage type. The restriction is part of the effect, not a footnote to ignore.

It is a target-side, follow-up-specific effect. By comparison, Robin’s Skill increases allies’ damage dealt. Read Topaz’s Kit and Robin’s Kit for the exact effects; this contrast is about their mechanics, not a team recommendation.

Applicable effects within the ordinary vulnerability family add together. A second qualifying 20% damage-taken effect adds 20 percentage points to that total; it does not automatically create another independent ×1.2 multiplier. Explicit stacking restrictions still apply.

Add within a family, multiply between the two

For this ordinary-hit comparison, the combined multiplier is (1 + B) × (1 + V). B is the sum of applicable DMG Bonuses; V is the sum of applicable vulnerability effects. Enter both as decimals, so 40% is 0.4. The examples use modest positive values and assume every listed effect is active and allowed to stack.

Give the hit a hypothetical value of 1,000 with these two families removed and all other factors held constant. That is our comparison baseline, not an in-game ATK stat or a prediction for a named Character.

With 40% DMG Bonus and 20% vulnerability, the arithmetic is 1,000 × 1.4 × 1.2 = 1,680. Combining them into one 60% total would incorrectly give 1,600. This multiplication describes the comparison; it does not specify the engine’s execution or rounding order.

The existing total changes the relative gain

Raising DMG Bonus from 40% to 60% increases our result from 1,400 to 1,600: about 14.3% more than before. Adding the first 20% vulnerability instead raises 1,400 to 1,680, a 20% increase. The percentage printed on an effect and the percentage gain over your current result answer different questions.

Vulnerability follows the same relative-gain logic within its own family. Raising it from 20% to 40%, with 40% DMG Bonus unchanged, takes 1,680 to 1,960: about 16.7% more. A less-filled family can offer a larger relative gain in a controlled comparison, but that does not make every vulnerability source better than every DMG Bonus source.

These figures assume equal coverage and no other trade-offs. A narrow effect helping one small part of the team’s damage can be less useful than a broader effect with a smaller percentage.

Do not copy this example onto every damage family

Break, Super Break, DoT, Elation and other specially defined damage need their own applicability checks. This guide’s ordinary direct-hit example does not establish which bonuses those sources accept. An effect explicitly limited to Break damage is not a general damage-taken increase for every hit.

Likewise, CRIT DMG, ATK increases and DEF reduction or RES PEN are not ordinary DMG Bonus just because they can increase a final damage number. Keep the named stat or mechanic attached to each percentage.

Match the effect to the damage plan

Identify the team’s important damage sources, then ask which attacker, target, Element and attack type each effect covers. Check whether it lasts through the relevant actions and whether applying it costs resources the team needs elsewhere.

Use Buffs, Debuffs and Cleansing to read effect conditions, then Team-building Fundamentals to connect those conditions to a rotation. A percentage matters when it improves the damage your team can actually deliver.