As per the BGTSCC wiki, the Shifter PrC states:
And per the BGTSCC wiki, (Epic) Dragon Shape states:- Special: If the character is a druid, Shifter levels progress Wild Shape uses per day. In addition to that, at Shifter level 15 character qualifies for Legendary Animal Shape and Epic Elemental Shape. Lastly, at level 20, he qualifies for Dragon Shape. Shifter levels stack with Druid levels to determine the power of Epic Wildshapes.
As I read it at least, Shifter levels stack with Druid levels for Epic Wildshapes, of which Dragon Shape is one.Type of feat: Druid, Epic
Prerequisite: Character 21, 25 druid levels or 20 Shifter levels (likely, in reality, 20 Shifter levels + 5 Druid levels)
Required for: No longer required for Dragon Companion (see page)
Specifics: The character may use wild shape to change into a dragon. The transformation has a duration of 1 hour per class level.
Use: Selected (must choose which type of dragon)
Dragon Shape varies in strength according to your druid level:
A level 30 druid becomes a 30 HD Dragon
A level 28-29 druid becomes a 28 HD Dragon
A level 27 or lower druid becomes a 25 HD Dragon.
Yet...testing in BG JEGs, a Druid 10 / Shifter 20 does not count toward a stacking 30 levels, and thus a 30 HD Dragon. Here is a screenshot of the Sheet:
Now...maybe this is intentional, that Druid 5 / Shifter 20 which unlocks the Dragon Shape feat for the taking, was to be limited to a 25 HD Dragon. If so, the wiki needs to be update, which I can do once it is confirmed to be intentional.
If it is not intended this way, then I'm requesting that Shifter and Druid levels DO stack to create a basis for a 30 HD Dragon (shape).
Also, though Dragon Shape requires 20 Shifter, when you are presented to take the final Wild Shape from this PrC at level 20, one cannot choose the Dragon Shape, where Shifter 15 unlocks the Legendary Animal and Epic Elemental shapes, and one CAN choose either Feat at Shifter 16. Maybe it is also intentional for Shifter to NOT be able to take Dragon Shape on lvl 20 Shifter...but that seems kinda odd.
Thanks for reading.