Alter Aeon Online Help

Keywords are:  'necromancer spell bonefortress fortress'

Spell: bone fortress            Mana:  72  Int: 32  Wis: 30  Lvl 31 Necr  (21%)
                                (helpful)   Requires: bone prison
                                Group: Necromancer Dragontooth Skills

Usage:
cast bone fortress

The 'bone fortress' spell is a high level necromancer tooth spell
used to rescue and protect entire groups when in danger.  It creates
a near-invulnerable fortress of bone around your group, separating
you from the enemy and offering temporary refuge.

You must be on solid ground to cast this spell, and it has a very
high tooth cost that increases as the size of the group increases.