Have you looked at door.lua?
Simply adding a check for dead monster at line 19 (ish) such as
if g_Entity[e]['plrvisible'] == 1 then
if bigScaryMonsterDead == 1 then
.
.
.
.
.
Development/ Gaming Rigs
Sys 1: i7-4770 (3.5)/16Gb/128 SSD/3Tb/970gtx/2 x 23, 1 x 27 LCD - Sys 2: i7/8Gb/670gtx/1.5Tb/1 x 23 LCD - Sys 3: Amd Quad/8Gb/645gtx/1Tb/30" LCD