We present Drile, a multiprocess immersive instrument built upon the hierarchical live-looping technique and aimed at musical performance. This technique consists in creating musical trees whose nodes are composed of sound effects applied to a musical content. In the leaves, this content is a one-shot sound, whereas in higher-level nodes this content is composed of live-recorded sequences of parameters of the children nodes. Drile allows musicians to interact efficiently with these trees in an immersive environment. Nodes are represented as worms, which are 3D audiovisual objects. Worms can be manipulated using 3D interaction techniques, and several operations can be applied to the live-looping trees. The environment is composed of several virtual rooms, i.e. group of trees, corresponding to specific sounds and effects. Learning Drile is progressive since the musical control complexity varies according to the levels in live-looping trees. Thus beginners may have limited control over only root worms while still obtaining musically interesting results. Advanced users may modify the trees and manipulate each of the worms.