fix(Core/Spells): simplify and fix Blood-Caked Strike calculation

[Tereneckla]

Changes Proposed:

This PR proposes changes to:

• Core (units, players, creatures, game systems).

Just add 50% total damage per disease (25% base + 12.5% per disease)

The extra damage per disease of Blood-Caked Strike now also will be normalized, as the base damage is.

SOURCE:

The changes have been validated through:

• Live research (checked on live servers, e.g Classic WotLK, Retail, etc.)
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• The changes promoted by this pull request come partially or entirely from another project (cherry-pick). Cherry-picks must be committed using the proper --author tag in order to be accepted, thus crediting the original authors, unless otherwise unable to be found

Tests Performed:

This PR has been:

• Tested in-game by the author.
• Tested in-game by other community members/someone else other than the author/has been live on production servers.
• This pull request requires further testing and may have edge cases to be tested.

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Known Issues and TODO List:

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[Copilot]

Pull Request Overview

Refactors the weapon damage calculation for Blood-Caked Strike to sum percentage modifiers instead of applying and multiplying raw damage, ensuring extra disease-based damage is normalized like the base.

• Introduces weaponDamagePercentMod to accumulate all percent-based weapon damage modifiers.
• Updates the Blood-Caked Strike branch to add disease-based percent instead of calculating and applying flat bonus damage.
• Removes the duplicate weaponDamagePercentMod declaration and changes how SPELL_EFFECT_WEAPON_PERCENT_DAMAGE updates the modifier.

Comments suppressed due to low confidence (4)

src/server/game/Spells/SpellEffects.cpp:3345

• [nitpick] The name weaponDamagePercentMod is very similar to totalDamagePercentMod and may be confusing; consider renaming to weaponPercentMod or weaponModAccumulator for clarity.

float weaponDamagePercentMod = 0.0f;

src/server/game/Spells/SpellEffects.cpp:3533

• The new Blood-Caked Strike percent-based logic isn't covered by existing tests; consider adding unit tests for 0–3 diseases to confirm correct percent accumulation and normalization.

if (m_spellInfo->SpellIconID == 1736)

src/server/game/Spells/SpellEffects.cpp:3345

• Initializing weaponDamagePercentMod to 0.0f will omit the base 100% weapon damage for spells without additional modifiers; consider starting this at 100.0f if you intend to include base damage.

float weaponDamagePercentMod = 0.0f;

src/server/game/Spells/SpellEffects.cpp:3575

• CalculateSpellDamage returns a raw damage value, not a percentage; adding it directly to weaponDamagePercentMod may lead to incorrect modifiers. Verify you're summing percent values rather than raw damage.

weaponDamagePercentMod += CalculateSpellDamage(j, unitTarget);

[sogladev]

Does the Blood-Caked Strike - Blood-Caked Blade spell require different handling than the ones above? Judging from the tooltips, they can be handled similarly

// Plague Strike
// Obliterate (12.5% more damage per disease)

If not, the same calcs should be done like below

AddPct(totalDamagePercentMod, disease_amt * unitTarget->GetDiseasesByCaster(m_caster->GetGUID());

[Tereneckla]

Very different. Obliterate increases the total damage per disease, Blood-Caked Strike adds straight 12.5% of the weapon percent per disease (or 50% total damage per disease)

[Tereneckla]

It came to me in a dream that spells such as Slam exist, starting the weaponDamagePercent at 0 would have made them do 0% weapon damage