Symbiotic 10 brings four substantial improvements. First, we extended our clone of Klee called JetKlee with lazy memory initialization. With this extension, JetKlee can symbolically execute a function without knowing its context. In SV-COMP, we use it to handle extern variables. Second, we have implemented the technique called compact symbolic execution to Slowbeast. Third, we have implemented a non-trivial may-happen-in-parallel analysis, which improves slicing of parallel programs. Finally, we have implemented support for violation witnesses in the new witness format 2.0.