I was playing with Hensiyn mystic over the weekend and i quite enjoyed it. It could do with some speed to stick enhancements and wis to damage/attack but overall i liked it, perhaps rolled into the capstone as it doen't follow the PrE's flavour at the moment.
Just an idea that i think would improve the flavour.
You are stuck with fire as a damage element, i'd like to see some savant style flexability on the element chosen.
I'd like to see Riddle of fire, incinerating wave and cauldron of flame changed to Riddle of elements, elemental wave and elemental tempest.
When you take riddle of elements you select an element and then all the other enhancements affected by the element, like ki bolt & Lighting the candle, follow this element; much like taking a sorc savant or draconic incarnation dragon type.
Elemental words already allows all element damage types to be augmented (its bugged, fire and ice vulnerability is swapped) so this change would make all the words useful dependant on Henshin Savant choice.
Just an idea, Dex