No retraining without good, story-driven reason:
No. Well, not without sidequest to reinvent yourself. So, not without extremely good story reasons and DM fiat.
The 1/encounter rage is from RobbyPants's homebrew Barbarian variant,
located here.
@Vinom: Do you ever play characters that
aren't dragon-themed? Just curious.
Honestly, if I were you, I'd just go back to playing a regular Cleric instead of reducing my power level by going mystic theurge, but hey, whatever floats your boat (and is allowed by the DM) *shrug*
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Ok, not that I would do it, but the idea of a Tibbit Siphoner is just hilarious. Sprinkles the Death-kitten destroys your soul by purring and rubbing against your leg!