Alter Aeon Online Help

Keywords are:  'mage skill maintaining spells maintenance'

Skill: maintaining spells       Lvl  9 Mage  (28%)
                                (important)   Requires: spell lore
                                Group: Mage basic magics

Usage:
maintain <spell name>
unmaintain <spell name>

The spell maintenance skill is used to keep certain spells up continuously,
so that they do not expire after a certain time.  Instead of needing to
recast the spell periodically, the spell saps a small amount of mana from
the caster for as long as the spell is up.  A spell maintained with the
'maintain' command can also be removed with the 'unmaintain' command.