This needs a bump. Remembering more than well that on live circa classic/Kunark era, I lost my shammy's level19 in Crushbone and wanted the spell level back real bad so I could keep shrinking in the Throne Room (due to ogres being unable to squeeze into the crush tower behind the chair). Also know it was pre-velious since I didn't hit 24ish on the shm until Velious opening, this was before that.
Shrink wasn't strictly an indoors thing, it was about zones flagged as dungeons.
Most hard to find proof of this though, grr.
http://web.archive.org/web/200107140...e=Shrink&type=
Last comment on that mentions Blackburrow being a zone where it works, ina year 2000!