So, we're talking about a homebrew...but D&D style...that can cast clerical spells as well? "spell/prayer book" So what's the spell slots/per day dispersion you're looking at for a "20th level Anything Caster."
Going just by most "iconic/traditional" that I would include (having recently spent considerable time paring down spell lists for my own homebrew system)...and, well, assuming a close-to-D&D spell progression of gaining a new level of spells every other level this'll get you up to a 10ish level caster...something in the neighborhood of 5 1st, 4 2nd, 3 3rd, 2 4th, 1 5th per day:
[Note: in my system
Light is a cantrip and
Read Magic is a normal Class ability of mages/wizards not a spell. So that's why they aren't there. If you want, swap out
Alarm for
Light since that's a pretty basic spell-castery trope
. Detect Magic is a cantrip also, but since I didn't know if you used them or not, I included it in the normal spell list since, I think, every spell-caster should/would have this power.]
1st level spells. . . . . . . .2nd level spells. . . . . 3rd level spells . . . . . 4th level spells . . . . . . . 5th level spells
1. Alarm . . . . . . . . . . . Detect Invisibility . . . Blink . . . . . . . . . . . . Charm Monster . . . . . . . Cloudkill
2. Burning Hands . . . . . .Detect Thoughts . . . Clairvoyance . . . . . . .Detect Scrying . . . . . . . Cone of Cold
3. Charm Person . . . . . .Invisibility . . . . . . . . Create Illusion II . . . . Dimension Door . . . . . . . Conjure Elemental
4. Comprehend Others . .Knock . . . . . . . . . . .Dispel Magic . . . . . . . Enchant Minor Items . . . .Create Illusion III
5. Create Illusion I . . . . Levitate . . . . . . . . . Fireball . . . . . . . . . . .Fire Shield . . . . . . . . . . .Dismissal
6. Detect Magic . . . . . .Mirror Image . . . . . . .Gust of Wind . . . . . . .Globe of Invulnerability . . .Feeblemind
7. Hold Portal . . . . . . . Pyrotechnics . . . . . . .Lightning Bolt . . . . . . Hallucinatory Terrain . . . . Fire/Ice Storm
8. Magic Missile . . . . . . Stinking Cloud. . . . . .Suggestion . . . . . . . . Polymorph [Self] . . . . . . . Passwall
9. Shield . . . . . . . . . . .Web . . . . . . . . . . . .Tongues . . . . . . . . . . Scrying . . . . . . . . . . . . .Teleport
10. Sleep . . . . . . . . . . Wizard Lock. . . . . . . Water Breathing . . . . .Wall of Fire/Ice . . . . . . . .Wall of Force
c1. Bless . . . . . . . . . . Chant . . . . . . . . . . .Continual Light . . . . . .Divination . . . . . . . . . . . .Commune
c2. Cure Wounds I . . . . Hold Person . . . . . . .Cure Disease . . . . . . .Locate Object . . . . . . . . .Cure Wounds III
c3. Remove Fear . . . . . Silence . . . . . . . . . .Cure Wounds II . . . . . Neutralize Poison . . . . . . . Dispel Evil
c4. Resist Fire/Cold . . . Slow Poison . . . . . . .Glyph of Warding . . . . Remove Curse . . . . . .. . . .Flame Strike
c5. Sanctuary . . . . . . .Spiritual Weapon . . . .Prayer . . . . . . . . . . .Restoration . . . . . . . . . . . Raise Dead
My system-in-progress actually uses lists of 12 arcane and 10 divine per spell level. But this covers all the bases [that I feel important for play, anyway] and should get you started for a while. Enjoy
