http://www.thegnomonworkshop.com/tutorials/creating-an-fx-production-shot-in-houdini

Follow along as FX Supervisor, Simon Littlejohn, creates a series of effects using Houdini and Nuke, from bone-crushing tendrils to a slimy tentacle attack. Simon approaches the workshop as the creation of a complete shot, from start to finish, revealing his processes and techniques along the way.  With over a decade of industry experience, Simon walks through his tried-and-trusted methods for procedurally generating curves using for-loops, and shows how to attach those curves to any animated character using simple yet powerful VEX. From there, he instructs how to “grow” those curves over time in visually interesting patterns, and ultimately create high-fidelity 3D geometry from them. The second technique in this workshop details how to create a slime trail left behind as the tendrils take over the character’s body. Simon shares how to create this highly controllable effect without the need for FLIP simulation, which can often be expensive and unpredictable.