Rerolling Charms  Resistance & MF Guide
By: St0rmie
Having gotten my Bowazon to Hell and found all my resistances in the
negatives, I've been trawling through the MPQs cooking up the odds on rerolling
charms (via the "magic item + 3 perfect gems = new magic item, same ilvl"
recipe) in the hope of getting resistance charms. Below is my little guide. You
may wish to read the executive summary, or if you're a hardened MPQdiver, I'd
appreciate it if you could glance over the gory details to see if my work looks
correct.
The Executive Summary
To reroll a charm, stick it in your Cube along with 3 perfect gems. Doesn't
matter what gems. Skulls are also fine. The possible affixes on the rerolled
charm are determined by the "ilvl" of the charm. This is the level of the
monster that dropped the charm, which in Nightmare and Hell difficulties is set
to the level of the area the monster is in, for all but a handful of monsters.
There is no way to determine the ilvl of an item*, so you need to remember where
you found your crap charms! Or better still, farm until you find one, and then
use that for rerolling.
If you want a shot at getting the best resistance charms there are to get,
farm for small charms in Travincal, the Forgotten Temple, the Ruined Fane
or the Disused Reliquary in Nightmare Act 3. The best you can get on a small
charm is +11% resist to a single element, or +5% resist all.
If you want a shot at getting the best resistance charms there are to get,
and also the chance of rolling a highly coveted +7% magic find charm, farm
for small charms in the Crystalline Passage, the Frozen River, the
Glacial Trail, the Drifter Cavern, or the Pit of Acheron in Nightmare Act 5.
If you want the greatest return on investment, in terms of number of resist %
points per perfect gem burned, farm for grand charms in the Blood
Moor, the Den of Evil, the Cold Plains, the Cave level 1 or the Burial Grounds
in Nightmare Act 1. The best you can get on a grand charm is +30% resist to a
single element, or +15% resist all.
If you want a good return on investment, if not the greatest one, and also
the chance of rolling a +1 to one skill tree charm, farm for grand
charms in the Great Marsh, the Flayer Jungle, the Arachnid Lair or the Spider
Cavern in Nightmare Act 3.
Farming these areas will provide the optimum level charms for rerolling. Charms
found later in the game will of course also be able to produce the same top
resist charms, but the chances will be reduced as they will have more affixes to
choose from. Of course these higher level affixes are all useful for other
purposes!
The best way to find charms is simply to kill as many monsters as possible as
quickly as possible. No monster has a "significantly" higher chance of dropping
one than any other monster, so just kill, kill, kill.
Additional useful tidbit: using these charms, there is no chance of getting a
"bad" resist all charm  the prefixes which provide lower resist all percentages
have maximum levels on them. This is only true for resist all, though  you
could still roll a low % resist to a single element.
* In Single Player play, you can use ATMA to
check the ilvl of an item. On the Realms, you may be able to use Maphack (I have
never used it, never will, and condemn anyone who does).
The gory details
Assumed knowledge: all resists on charms are prefixes, and magic items have a
50% chance of having a prefix (50% have suffix only, 25% have prefix only, 25%
have both). So any resist charm you come up with has a 50% chance of also having
a suffix, which may or may not be useful.
Small Charms
Best resists are alvl=40 (amber, emerald, ruby, sapphire: +1011% to one
element)
Shimmering (+35% resist all) is alvl=33
To get alvl=40 affixes, need charm of ilvl=54. At this ilvl:
Chance of a prefix being a shimmering or a +1011% resist is 9/91 = 4.95% per
reroll
Chance of a prefix being a shimmering or a +811% resist is 17/91 = 9.34% per
reroll
Chance of a prefix being a shimmering or a +611% resist is 25/91 = 13.74% per
reroll
Chance of a prefix being a shimmering or a +311% resist is 33/91 = 18.13% per
reroll
Large Charms
Best resists are alvl=35 (amber, emerald, ruby, sapphire: +1315% to one
element)
Shimmering (+68% resist all) is alvl=34
To get alvl=35 affixes, need charm of ilvl=42. At this ilvl:
Chance of a prefix being a shimmering or a +1315% resist is 9/137 = 3.28% per
reroll
Chance of a prefix being a shimmering or a +1115% resist is 17/137 = 6.2% per
reroll
Chance of a prefix being a shimmering or a +815% resist is 25/137 = 9.12% per
reroll
Chance of a prefix being a shimmering or a +415% resist is 33/137 = 12.04% per
reroll
Grand Charms
Best resists are alvl=30 (amber, emerald, ruby, sapphire: +2630% to one
element)
Shimmering (+1315% resist all) is alvl=35
To get alvl=35 affixes, need charm of ilvl=35. At this ilvl:
Chance of a prefix being a shimmering or a +2630% resist is 9/161 = 2.8% per
reroll
Chance of a prefix being a shimmering or a +2130% resist is 17/161 = 5.28% per
reroll
Chance of a prefix being a shimmering or a +1630% resist is 25/161 = 7.76% per
reroll
Chance of a prefix being a shimmering or a +730% resist is 33/161 = 10.25% per
reroll
Conclusion
Small charms clearly provide the best resist charms. Better resist density
possible (11/square vs. 7.5 for large and 10 for grand charms), equal or better
resist all density possible (5/square vs. 4 for large and 5 for grand charms),
and more flexible. However, although small charms give the best potential,
squareforsquare, the fact that three times as many good ones need to be rolled
means this will be more expensive in perfect gems. As seen below, grand charms
give the best return on investment.
Average "resistance per reroll" for a small charm
Shimmering = 35 x 4 = 16 avg x 1/91 x 1/2 = 0.0879
1st tier resist = 1011 = 10.5 avg x 8/91 x 1/2 = 0.4615
2nd tier resist = 89 = 8.5 avg x 8/91 x 1/2 = 0.3736
3rd tier resist = 67 = 6.5 avg x 8/91 x 1/2 = 0.2857
4th tier resist = 35 = 4 avg x 8/91 x 1/2 = 0.1758
Total average = 1.3846% resists per reroll
Average "resistance per reroll" for a large charm
Shimmering = 68 x 4 = 28 avg x 1/137 x 1/2 = 0.1022
1st tier resist = 1315 = 14 avg x 8/137 x 1/2 = 0.4088
2nd tier resist = 1112 = 11.5 avg x 8/137 x 1/2 = 0.3358
3rd tier resist = 810 = 9 avg x 8/137 x 1/2 = 0.2628
4th tier resist = 47 = 5.5 avg x 8/137 x 1/2 = 0.1606
Total average = 1.2701% resists per reroll
Average "resistance per reroll" for a grand charm
Shimmering = 1315 x 4 = 56 avg x 1/161 x 1/2 = 0.1739
1st tier resist = 2630 = 28 avg x 8/161 x 1/2 = 0.6957
2nd tier resist = 2125 = 23 avg x 8/161 x 1/2 = 0.5714
3rd tier resist = 1620 = 18 avg x 8/161 x 1/2 = 0.4472
4th tier resist = 715 = 11 avg x 8/161 x 1/2 = 0.2733
Total average = 2.1615% resists per reroll
Using ilvl=50 grand charms will dilute the prefix pool by increasing the prefix
frequency total from 161 to 230 (making resist charms only 70% as likely), but
(1) the average amount of resists per reroll will still be higher than for
optimum ilvl small charms, (2) +1 to skill tree charms will become possible, and
(3) the "of Subsistence" suffix (+2630 to life) will become available. You
should get approximately one top tier resist or +1 skill tree charm every 15
rerolls.
Using ilvl=61 small charms will dilute the prefix pool only a tiny amount,
increasing the prefix frequency total from 91 to 93 (making resist charms only a
little more than 2% less likely), but opens the possibility of the "of Good
Luck" suffix (+67% magic find). The chance of a suffix being "of Good Luck" is
2/65, and given that 75% of magic items have a suffix, the actual chance per
reroll should be 2.308%. The chance of a perfect "+7mfsc" is of course half
that, 1.154%. Obviously a Shimmering Small Charm of Good Luck is as unlikely as
it is desirable.
To find ilvl=35 grand charms, farm Blood Moor, Den of Evil, Cold Plains, Cave
level 1 or Burial Grounds in Nightmare difficulty. Actually these areas are all
level 36, but this doesn't add any new affixes over ilvl=35.
To find ilvl=50 grand charms, farm Great Marsh, Flayer Jungle, Arachnid Lair or
Spider Cavern in Nightmare difficulty.
To find ilvl=54 small charms, farm Travincal, Forgotten Temple, Ruined Fane or
Disused Reliquary in Nightmare difficulty.
To find ilvl=61 small charms, farm Crystalline Passage, Frozen River, Glacial
Trail, Drifter Cavern, or Pit of Acheron in Nightmare difficulty.
Magic Finding
The "of Good Luck" suffix (+67% magic find) on a small charm is alvl=47. To get
alvl=47 affixes, you need a charm of ilvl=61. To get ilvl=61, the earliest place
to farm is Crystalline Passage, Frozen River, Glacial Trail, Drifter Cavern, and
Pit of Acheron in Nightmare Act 5.
Given a charm of that optimal ilvl, the chance of a suffix being "of Good Luck"
is 2/65, and given that 75% of magic items have a suffix, your actual chance per
reroll should be 2.308%. That's for +67% MF, so if you demand the full +7%, the
chance per reroll will be 1.154%.
One in three mfsc's will also have a prefix.
Conclusion
The best resistance small charm affixes, for example, require only ilvl 54.
There's no need to have an ilvl 85 charm if you just want resistances, and since
some nonresistance affixes get introduced at these higher levels, your chance
of getting the resistance ones will actually go down.
Of course, if those highlevel affixes are what you want, go ahead with the
highlevel charms. The ones from Baal would be ilvl 99, higher even than those
from the level 85 areas.

