Blindness not working at all

[chaoticneutral07]

Subject: Bug Report: Blindness and Monk of the Dark Moon "Darkness" mechanics

1. Wizard Spell: Blindness (2nd Level) Issue: The spell is completely non-functional. Details: Upon a failed saving throw, the target does not receive the "Blind" status effect. There is no icon, no reduction in visual range, and no mechanical penalties applied to the target's Armor Class or Attack Bonus. It behaves as if the effect is blocked or missing.
2. Monk of the Dark Moon: Darkness Ability. Issue A (Infravision Logic): The ability currently only affects creatures with Infravision (applying a -4 penalty). However, it has no effect on "Human" types or any creatures without Infravision. In D&D mechanics, creatures without Infravision should be affected more severely (total blindness) or at least receive the same penalties. Currently, they are completely immune. Issue B (Scaling DC): The description states that the Difficulty Class (DC) should increase by half of the Monk's level. My testing shows this is not being calculated. The DC remains static (15 + Wisdom Modifier), ignoring the level-based bonus. Issue C (Combat Log "Trash"): When checking saving throws in the combat log, the game output is corrupted or displays incorrect strings instead of a clear "Saving Throw vs Spell" message.

[FK-dot]

The Darkness ability for both Drow and Tieflings has the same issues, leading to FPS drops. Also, the Drow’s Faerie Fire can be cast at any point within its range, which is strange for a spell that targets a single creature.

[WillScarlettOhara]

Did some source-diving (v3.4.2). Two of the three symptoms share one root cause.

Root cause (Blindness #1 + Darkness-on-non-infravision #2A)

iwd2ee/ieex_override/IEex_Opcode_State.lua:260, inside the EXEFFMOD
handler registered to IEex_Extern_OnCheckAddScreenEffectsHook:

if opcode == 40 or opcode == 74 then return true end

In this hook, return true means "handled — engine skips its default
application" (same convention the immunity loop and the rest of EXEFFMOD use).
There is no Lua reimplementation of opcodes 40 (Slow) or 74 (State: Blind),
so both are silently dropped: the engine never applies them and nothing
replaces them.

git blame points at commit 2b0e0a8 ("Version 3.4.0", 2025-12-11), so this
looks like a 3.4.0 regression. The line is still present in 3.4.2.

That single line explains:

• ALIGNMNT.2da #1 Wizard Blindness — the spell relies on engine opcode 74; it's blocked,
  so no Blind state, no icon, no AC/attack penalty. Matches "as if blocked."
• #2A Darkness immune to non-infravision creatures — MEDARKNE
  (IEex_IWD2_State.lua:7582) chooses the penalty from
  ex_darkvision_attack_penalty (IEex_WEIDU.LUA:42 = {[0]=-99,[1]=-4,[2]=-2,[3]=0,[4]=-99}).
  A target with no darkvision (level 0) maps to -99, whose branch applies
  opcode 74 — which is then swallowed by line 260 → appears immune. Targets
  with darkvision level 1 get opcode 54 (−4 attack), which is not blocked →
  hence "only affects infravision creatures with −4." The darkvision tables
  themselves look correct.

The FPS drop @FK-dot mentions is consistent with the darkness effect re-applying
opcode 74 every tick because it never "sticks."

Suggested direction: let opcode 74 through again (the darkness loop, if it
was the original reason for the block, should be fixed at the MEDARKNE
reapply guard rather than by blocking all blindness globally).

#2B — Darkness DC not scaling

Separate issue. MEDARKNE doesn't compute a DC; the save DC comes from
USDARMO.SPL, which carries a fixed value. There's no effect adding +½ monk
level, so the DC stays at the base. Needs a level-scaling component.

#2C — Combat-log "trash"

Also separate. The opcode→feedback-string map (IEex_IWD2_State.lua:18409,
[74] = {0x9DA, 2} → strref 2522) looks intact, so the corruption is probably
downstream in how the save-throw string is formatted/emitted, not the mapping.

(All from reading the source, not runtime traces.)

If anyone can share a savegame that reproduces this, I'm happy to dig in and
test fixes locally to confirm before anything is changed.