Its not really a problem of 'needing' the DM to screw the wizard. Most parties
will be captured or otherwise stripped of their gear, at least once in their career. For a wizard without some backup spell-book, that simply spells doom. For a wizard with a tattooed spell or two, or a wizard with Spell Mastery, the spells may be enough to tide his over until the party recovers or captures another spell book.
The problem with the Spell Mastery feat as written is that it does not scale -- spells that are useful at low levels are quickly overshadowed at higher levels.
For example, it would be wise for a 7th level wizard to keep a second copy of the
dimension door spell on him, in order to escape if ever captured. However, at 9th level the
teleport spell will take over this role, and then by
greater teleport or even
gate (just use the spell twice). If you took Spell Mastery for the
dimension door spell, it becomes a sub-optimal choice within two levels, and mostly worthless in four levels time.
The same thing happens with most other useful spells:
dispel magic gives way to
greater dispel then to
reaving dispel;
alter self advances to
polymorph and then to
shapechange; so on and so on. The way D&D magic is designed, a spell's effectiveness is capped, and then its role taken over by a higher level spell. So with Spell Mastery, you are swiftly stuck with a list of mastered spells that you will never use.
Your change is good, IMO, because it begins to address the scalability issue -- one spell per class level ensures that the wizard will always have a useful spell among his spells mastered.
So, with that in mind, here's another way to make the feat scalable. Treat the 'spells mastered' more like slots to be filled. The wizard gains 3 + Int mod 'slots', which he can fill with 'mastered' spells i.e. spells learned by heart. He may spend 1 day per spell level of the new spell to memorize a new spell, but he forgets one old 'mastered' spell if he does so. Basically, the wizard's mind becomes like 3+ Int mod pages from a baccob's blessed book, except that the 'mind-pages' can be erased and rewritten.
Code:
[FONT=Times New Roman]SPELL MASTERY [SPECIAL]
[b]Prerequisite:[/b] Wizard level 1st
[b]Benefit:[/b] Each time you take this feat, choose a number of spells
equal to three plus your Intelligence modifier (minimum one spell) that
you already know. From that point on, you can prepare these spells
without referring to a spellbook.
You can swap a previously mastered spell out in order to master new
spells. In order to do so, you must spend 1 day per spell level of the new
spell to be mastered studying your spellbook, attempting to commit the
complex formulas, chaunts, gestures and/or rituals to memory.
You spend 8 hours each day studying. If your study is interrupted,
you must spend one extra hour that day for every 30 minutes of the
interruption. If you are interrupted for more than 2 hours in one day,
your attempt to master the new spell fails, but you can always try again.
If you are not too severely interrupted, you may make an Intelligence
check (DC 15 + the spell level of the new spell) at the end of the duration
of study. If you succeed, you lose mastery of one previously mastered
spell (chosen by you) and gain mastery of the new spell.
[b]Normal:[/b] Without this feat, you must use a spellbook to prepare
all your spells, except read magic.[/FONT]
I think if I were a wizard, I would still rather just tattoo a backup spell or two on my own body (on the soles of my feet, perhaps). You do not actually
need so many backup spells -- just enough spells to get you back home (where, persumably, you have stored an extra spell-book or three). Still, the above version does make the Spell Mastery feat less useless, so I might try floating it next session.
