  Our knowledge of the dynamics of stars has undergone a revolution thanks to
the simultaneous large amount of high-quality photometric observations
collected by space-based asteroseismology and ground-based high-precision
spectropolarimetry. They allowed us to probe the internal rotation of stars and
their surface magnetism in the whole Hertzsprung-Russell diagram. However, new
methods should still be developed to probe the deep magnetic fields in those
stars. Our goal is to provide seismic diagnoses that allow us to sound the
internal magnetism of stars. Here, we focus on asymptotic low-frequency gravity
modes and high-frequency acoustic modes. Using a first-order perturbative
theory, we derive magnetic splittings of their frequencies as explicit
functions of stellar parameters. As in the case of rotation, we show how
asymptotic gravity and acoustic modes can allow us to probe the different
components of the magnetic field in the cavities where they propagate. This
demonstrates again the high potential of using mixed-modes when this is
possible.
