It's deep, but virtually unguarded spawn at -- Loc: 585 x N1140 x N955.
And then just after that is Vergalid's cave. There are about a half dozen D-shroom spawns in this cave, all unguarded - however....
"If I knew then what I know now"...
Get to keyed area, go thru to Pit spiral, Levitate, go to bottom, loot 2 shrooms unmolested, "gate out" - (see below).
If Vergalid is up he can help or hinder you. Don't get too close to him BEFORE you have your 2 shrooms. But after you do, get near him and he boots you right back up to the elevator / ZI - woot! -- very nice -- free succor for any class.