Heh, i was actually playing around with this exact command myself, i found a file called dlighth in the HL sdk, which seems to have the same charachteristics the Dlight tempentity (dynamic lighting) except theres an option to darken instead of lighten, however i have no idea how to actually use it, if it even can be within amx(x). I put a post on the amxmodx forums for this and if i get a reply or find anything i'll let you know