As a concept designer, your toolbox has to grow since you never know what project you may need to tackle. Recently, I decided to add Houdini to the collection, especially since it will play an important role as a VFX engine in one of AK-ART's IPs, SimRa. From concept art standpoint, it's also invaluable in VFX design, since it's procedural pipeline gives you fast and intricate results that would be very time consuming with regular 3D modeling.
After several weeks of an intensive course at CGSociety, I just scratched the surface, since there is sooo much more to this powerful app. But you have to make the first step, right? A small "demo reel" made out of short animations will be posted soon and in the meantime, here are some caps.