Sometimes I find it difficult to understand the meaning of the messages in the combat log. I create this thread to clarify those messages with a less obvious meaning.
I start with "One of the spells has failed". I get that message about twenty or thirty times when fighting the Balor in the svirfneblin settlement in the Underdark (BG2). It appears every time I hit the Balor with anything, either weapons or spells. It seems similar to the messages about disrupted casting, but AFAIK spells don't get disrupted when you're hit by a spell like Breach.
So what does it mean?
In case it's relevant, I have several mods installed, including SCS.
Messages explained so far
One of the spells has failed: A contingency or sequencer was fired out of range of the spells it contains.
<creature1>: Casts <spell>: <creature2>. For example: Ulitharid: Casts Dimension Door: Ulitharid. Creature 1 has cast a spell on creature 2.
<creature1>: <spell or ability>: <creature2>. Same as above, but without the word "Casts". For example: Ulitharid: Psionic domination: Haer' Dalis. This can have several meanings:
An Innate ability was used.
A spell was cast using a contingency or sequencer.
The AI cheated, forcing a spell without memorization or interruption.
Weapon ineffective: Your target is immune to the weapon you're using. There can be two reasons for this:
Your target is naturally immune to the weapon you're using. This is common in magical monsters.
Your target is protected by a spell that protects against some kinds of weapon, like Protection from magic weapons or Mantle.
<creature> was immune to my damage. The creature is immune to the type of damage you're using against it. Example: You attack a clay golem with a magical sword. Clay golems are immune to the slashing damage of swords, so you get the message Clay golem was immune to my damage.
<creature>: unaffected by effects from <item>: The creature is immune to some or all the effects of the item or spell that was used against it.
<creature>: Dispel effects: The creature was in the area of effect of a Dispel Magic or Remove Magic spell. Note that this message doesn't mean that anything was dispelled, it is displayed even when the dispelling fails to dispel anything.