I'm trying to forget Fortress of Ice in Throne City and the following happens:

> ask flein about erase
Fleintoore nods and says, "Spell erasure is unique process in which our scribes help you forget the knowledge of spells you may no longer wish to keep. For practical purposes, you may not erase a spell that is a prerequisite for other spells you already know -- for example, you may not erase Lightning Bolt if you know Chain Lightning. The fee for this service is partially subsidized by the guilds and is variable based on a number of factors. You'll no doubt be happy to know that we donate five percent of all sales of this service to the continued restoration and beautification of historic Throne City. If you decide on a spell you wish to forget, we'll sit down together and calculate the fee."
[To purchase this service, type CHOOSE <spellname>. You will lose that spell from your spellbook but will regain the spell slot(s).]
> CHOOSE Fortress of Ice
Fleintoore ponders for a moment, then reviews a massive spellbook from a nearby shelf. After much page-turning, he finally looks up and says, "You don't have anything like that in your spellbook, Mazrian."

> prep foi
You sense an instability in the spell pattern that may prevent it from working.
Since you're not feeding enough power into the spell pattern to make it coherent, you quickly work your way to the minimum required.
That won't affect your current attunement very much.

You trace an angular sigil in the air, shaping the pattern of the Fortress of Ice spell.
>

Oddly, PREP seems to recognize the abbreviation but not the full spell name.

> prepare Fortress of Ice
You have no idea how to cast that spell.


What do?


Mazrian