monsters are summoned via the Shadow Creatures spell.
The no_immobile tag can be used to cause summoned immobile monsters to be immediately culled after they're summoned.
git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@8111 c06c8d41-db1a-0410-9941-cceddc491573
WGM77XP66ZEIRWAOKAJDICJ4ZBEUKGAEY6MZQQJ2LUWG5PCG722QC