Out of curiosity, what's the "expected" way of dealing with map 21?
My method was:Finding no secrets probably didn't help things any.
Also, Map 24- I haven't finished this one yet (best attempt yet was killed by the Cyberdemon), but the enemy placement in the Yellow Key area is bizarre. A few Lost Souls that can't attack you through the impassible lines, then a trap of Pain Elementals that can't attack you because of those same impassible lines? What?