From the Arch-Magi answers page on the official EQ site
Q: How do spell fizzles (and missed notes on songs) work?
A: When you cast a spell, we call a fizzle check. There is always a 5%
chance of succeeding (regardless of how low your appropriate skill is) and a
5% chance of failure (regardless of how high your appropriate skill is).
What modifies a fizzle check are (a) your appropriate skill (Abjuration,
Evocation, Brass, Wind, etc.) (b) your primary statistic (Intelligence for
Magi, Wisdom for Priests, Dexterity and Charisma for Bards) (c) the
difficulty of the spell and (d) the level of the spell.
When you gain a new rank of spells, any spell that you cast of that rank has
a 20% chance of fizzling. This assumes that (a) your appropriate skill
(Evocation, for example) is at its maximum value (b) that you have a minimum
of 75 in your appropriate statistic (Intelligence, etc.) and (c) that we did
not set the difficulty of the spell to less then average (some spells we
assign a lower difficulty, making them easier to cast - to date, we have not
made any spells with higher difficulty).
If your appropriate statistic is greater then 75 (Intelligence, Wisdom,
etc.), we reduce your fizzle percent by 1% for every X points of your
statistic above 75.
Each spell assumes that you have a skill equal to (5 * level you go the
spell). A Wizard getting Bind Affinity (Wizard gets her 4th rank spells at
level 12, so 5 * 12 =60) would have that spell assuming that she had a 60
Alteration skill for purposes of casting. With a 60 skill in Alteration (the
appropriate skill) and a 75 intelligence, our wizard would have an 80%
chance of successfully casting Bind Affinity. For every skill point that our
Wizard has above 60, the percent chance of fizzling goes down by 1%, to a
minimum of a 5% chance of fizzling. Thus, three levels (15 skill points)
after our Wizard gets Bind Affinity, she will be able to max out her
Alteration and have a mere 5% chance of fizzling the spell.
A high intelligence would help her to max out her ability to cast Bind
Affinity without fizzling earlier.
Rokenn Swiftsong - Karana server
EQ Bard Song Analysis
http://rgonzalez.net/EQSongs/