Alter Aeon Online Help

Keywords are:  'spellresistances spres magicresistances resistances magresistances'

Spell resistance is one of four major classes of defenses against
magic and spellcasting.  As a quick summary, those classes are:

1) Null magic resistance (extremely rare)
2) Spellsave - chance that a spell will fail or be less effective
3) Spell resistance - reduces the level of all spells cast on you
4) Magic absorb - absorbs magical damage and converts it into mana

Spellsave is most effective against dispel magic and curses. It also
reduces magic damage, including blows from magic damage weapons,
spells that do raw magical damage (such as magic missile and many
illusion spells) and special magical attacks.

Spell resistance universally affects all spells cast on a target,
and lowers the level of the spell before it takes effect.  This is
usually used as a first line of defense - high level spells are
weakened to half their initial level or lower by spell resistance,
making spellsave vastly more effective against the lower level spell.

Note that spell resistance items are very limited in range, and can
only protect small areas.  In order to get reasonably high spell
resistance, it is necessary to have resistance on equipment in
different wear locations scattered about the body.  Wearing hugely
protective rings and gloves will not help protect your head, for
example.

If you find that wearing additional spell resistance items does not
help raise your spell resistance, you may need to put it on different
wear locations.  The maximum spell resistance is 90, which cuts the
level of incoming spells by a factor of around 2.5.