Does anyone know, which file contains the sound effects of WC2?
They are within the WING2.TIM file. The file has three blocks dividing the effects by audio format: MIDI, SoundBlaster, PC Speaker. If you unpack the TIM file and view the content of individual files (ex: WING2.TIM-Block000Midi-Audio009.tim), you will see the effect name.
There is also the file FX.000 which as to do with sound effects, but I have no idea what it does. It seems specific to the cinematic scenes only.