  We revisit the concept of chiral disorder in QCD in the presence of a QED
magnetic field |eH|. Weak magnetism corresponds to |eH| < 1/rho^2 with
rho\approx (1/3) fm the vacuum instanton size, while strong magnetism the
reverse. Asymptotics (ultra-strong magnetism) is in the realm of perturbative
QCD. We analyze weak magnetism using the concept of the quark return
probability in the diffusive regime of chiral disorder. The result is in
agreement with expectations from chiral perturbation theory. We analyze strong
and ultra-strong magnetism in the ergodic regime using random matrix theory
including the effects of finite temperature. The strong magnetism results are
in agreement with the currently reported lattice data in the presence of a
small shift of the Polyakov line. The ultra-strong magnetism results are
consistent with expectations from perturbative QCD. We suggest a chiral random
matrix effective action with matter and magnetism to analyze the QCD phase
diagram near the critical points under the influence of magnetism.
