DrainSoulTimer is a fairly simple addon. It can make a sound when your target enters “execute” range (below 25%) and fire a sound when a Drain Soul ticks. At the time of this writing the most updated version is found in WowInterface and is compatible with patch 3.3.
The addon’s setup screen allows you to turn the execute/tick sounds on/off and to configure how much health a mob has to have to fire the execute range(so that the execute sound only fires for non-trash mobs). I couldn’t find any way to configure -what- sounds are used (aside from editing the .lua directly)(which I wasn’t interested in doing). I decided I didn’t need the execute warnings to fire (I already us Power Auras for that) so I turned it off. At this point the addon is making a noise when I’m channeling Drain Soul and it ticks. This allows me to more easily time the refresh of any other spells to after a tick has occurred.
Originally I thought I would be able to get Mik’s Scrolling Battle Text to do this.. but I spent about an hour trying to configure it and I couldn’t get it to fire sounds. It was flashing the text warning at me.. and it -looked- like it should have been making noise.. but the noise never happened. So I gave up and downloaded this addon. I figure I probably have an addon conflict.