  Symmetry-protected topological semimetals are at the focus of solid-state
research due to their unconventional properties, for example, regarding
transport. By investigating local two-band Bloch Hamiltonians in the spin-1/2
basis for the 122 magnetic point groups, we classify twofold-degenerate band
touchings such as Weyl points, robust nodal lines on axes and in mirror planes,
and fragile nodal lines. We find that all magnetic point groups that lack the
product of inversion and time-reversal symmetries can give rise to
topologically nontrivial band touchings. Hence, such nodes are the rule rather
than the exception and, moreover, do not require any complicated multiband
physics. Our classification is applicable to every momentum in the Brillouin
zone by considering the corresponding little group and provides a powerful tool
to identify magnetic and nonmagnetic topological semimetals.
