Eremite
Explorer
I seem to recall that there was an "official" ruling that casting shapechange or polymorph didn't affect your hit points despite it affecting your Con. I think it may have been a Sage ruling.
Of course, being a Sage ruling, it was then followed with another Sage ruling stating the opposite but, again, I trust that I am recalling this correctly.
The argument presented for not changing the hit points was the difficulty of recalculating hit points each round as a change was made and also because sometimes hit points would be reduced rather than increased.
I'll see if I can find this on the WotC site....
Of course, being a Sage ruling, it was then followed with another Sage ruling stating the opposite but, again, I trust that I am recalling this correctly.
The argument presented for not changing the hit points was the difficulty of recalculating hit points each round as a change was made and also because sometimes hit points would be reduced rather than increased.
I'll see if I can find this on the WotC site....