  The phase diagram of strong interaction matter is analyzed utilizing the
Nambu--Jona-Lasinio model. Special emphasis is placed on its dependence on an
external magnetic field and isospin chemical potential. Using flavor mixing
induced by instanton effects the influence of isospin breaking due to the
magnetic field and the isospin chemical potential is compared. It is found that
at low temperatures and large quark chemical potential the magnetic field,
depending on its strength, induces a new critical endpoint or a triple point.
