IMShadow did a very good job at voicing Trixie. The voice pack contains magic duel lines, as well as the quotes for when Trixie is using the Alicorn Amulet.

Link: http://www.mediafire.com/download/rntcboxcxspnxvt/Trixie+Voice+Pack+by+IMShadow007.zip

MLP by Hasbro