Eldrich Master is a prestige class from dragon mag 280. It does not progress spell casting, but at levels 4 and 8 it gets to add another spell list to its own. It also gives a bonus metamagic feat at 3rd, and gives you a spell slot one level higher (and a spell known) than you can currently cast at 3rd (giving a 3rd level bard spell). Additionally it gives bonus spells known, and adds to your affective caster level for all your arcane classes. Here is a simple build.
Bard 4/ Cleric 1/Dweomerkeeper 1/ Eldrich Master 4/ Sublime Chord 1/ Dweomerkeeper 9
Cleric of mystra or Thoth for magic and rune* domains
L1 Dragonwrought Kobold
L3 Extend Spell
L5 Scribe Scroll*
L6 Alternative Source Spell
L9 Persistent Spell
L9 Divine Metamagic
L12 Practiced Spell caster (sublime chord)
L15 Easy Metamagic (Lowers Persistent Spell by 1)
L18
This will net you Sorc, bard, and Cleric spells from levels 4-9th. You can cast these spells with divine metamagic using alternative source spell to convert them to divine. I am assuming you are using ebberon dragon templates to get druid, not sure if that still applies in this build.
The next trick is to use the spells from the Abyssal book to swap out feats (Embrace the dark chaos/shun the dark chaos). Swap out your cleric armor feats to pick up Extra spell slot. The feat says it can give you any spell slot up to one level lower than the highest level spell you can cast. Swap out 3 feats to pick up a 1st, 2nd, and 3rd level spell slots for the sublime chord. Note Eldrich master also gives bonus spells known from levels 1st through 4th. Convince your DM to let you hold those bonus spells until after you take sublime chord and do the feat swap. Now you can cast spells from 1st to 9th with a caster level of 18, 22 effective. Note there are a ton of spells that add cha for good casters. Snowsong L6, Inner Beauty L4, Sirines and Nixie’s Grace L4 and L6, Transfusion L5 Dragon mag, Greater Visiage of the Deity L9. It is really easy to push your Cha well past 50 (giving you plenty of turnings for divine metamagic).
Edit: You can try and copy the archivist list for all divine spells, but technically they don't have their own list. Same goes for the Chameleon which has all divine and arcane spells.