Written by Eric Berlin
The trigrams (three-letter groups) can be arranged to form a list of monsters (most of them familiar, and all of them findable in the AD&D Monster Manual.) Each monster, however, is missing one letter. The correct order of trigrams is as follows:
z(O)mbieThe missing letters, taken in order, spell ONE AFTER FIFTH. The answer to the puzzle is thus sixth.
ce(N)taur
vampir(E)
chimer(A)
e(F)reet
skele(T)on
m(E)dusa
minotau(R)
grif(F)on
wra(I)th
mind (F)layer
(T)roll
s(H)rieker