The next generation of lasers will access intensities above 10^23 W/cm^2. When plasmas or relativistic electron beams interact with these lasers, energy loss due to radiation emission, or quantum effects such as electron-positron pair creation become important for their dynamics. Repeated occurrence of pair creation can induce a so-called “QED cascade”, that generates an exponentially rising number of particles. This allows for creating exotic plasmas that are a mix of electrons, ions, positrons, energetic photons and intense background fields. Extreme laser-plasma interactions can be explored to form optical traps, create&accelerate particles and produce novel radiation sources. I will introduce a QED module coupled with the massively particle-in-cell framework OSIRIS that allows studying nonlinear plasma dynamics in the transition from the classical to the quantum-dominated regime of interaction. Simulating these enviroments brings novel computational challenges, which will be discussed along with the proposed solutions.