Can you use Dragon Magic & Complete Mage?
If your DM allows Dragonfire Adept to qualify for Eldritch Disciple, you can get in with Cleric 3/ DFA 2 and after 10 Levels(ECL 15, if no LA or racial HD) you're looking at 13/13 Invocations & Divine Spells, a 6d6 Breath Weapon(cone of fire or 1 2nd-Level effect of your choice) + a few "Gifts of your Divine Patron" to power with your Turn Undead.
Sounds promising...
Sorry, I reread the class and must correct myself. A player used it this way in one of my games, it wasn't broken and so I never checked his interpretation:
RAW you only get new Invocations, no increase in Breath Weapon damage or range.
Suggested fix:
If you can get your DM to accept Breath Weapon = Eldritch Blast, you still loose out on Breath effects. But at least it works out as I wrote in my above post.
Nothing overpowered here, anyways, just really good area-healing(Healing Blast: 6d6 in cone for 1 use of Turn undead, should hit your whole party + pets/cohorts if used out of combat), assuming you're CG(basically that is the best alignment, as it also allows you to get Protective Aura and Wild Frenzy with nicely boost your defense and offense in melee).
You need high CON(for Breath Weapon DC), CHA(Invocations, Gifts & Turn Undead) and WIS(cleric spellcasting).
No easy way to reduce MAD,
short of becoming Undead to use CHA instead of CON and/or replacing Cleric with Shugenja+some PrC that grants Turn Undead(Sacred Exorcist, for example)