1-2

1 chuul lurking in a pool of water. If it's in its lair then it has the following treasure: Roll on "Ambusher treasure (OotA Subtable)"

3

Roll 1d6 giant spider(s) clinging to the walls or ceiling. If it's in its lair then it has the following treasure: Roll on "Ambusher treasure (OotA Subtable)"

4-5

1 grell floating near the high ceiling. If it's in its lair then it has the following treasure: Roll on "Ambusher treasure (OotA Subtable)"

6-9

Roll 1d4 grick(s) hiding in a crevice or fissure. If it's in its lair then it has the following treasure: Roll on "Ambusher treasure (OotA Subtable)"

10-15

Roll 1d4 orog(s) perching on ledges. If it's in its lair then it has the following treasure: Roll on "Ambusher treasure (OotA Subtable)"

16-17

Roll 1d6 piercer(s) masquerading as stalactites. If it's in its lair then it has the following treasure: Roll on "Ambusher treasure (OotA Subtable)"

18-20

1 umber hulk bursting out of nearby wall. If it's in its lair then it has the following treasure: Roll on "Ambusher treasure (OotA Subtable)"