FL Slayer is a guitar virtual instrument by Image-Line Software. It comes with several options for tweaking the sound and a few dozen presets. Although this sounds like it would be great, the sound is ugly, difficult to use, and not very versatile. You have to put in a ton of work to make it sound good, and overall that really doesn't amount to a good tradeoff. It's not worthless, but certainly not something one would use often.