  We predict giant susceptibility of spin-bifurcating polariton condensates to
externally applied permanent magnetic field. In the presence of
spin-anisotropic polariton-polariton interactions, the condensate spontaneously
takes an elliptically polarised state, {whose perturbation dynamics can be
interpreted in terms of the presence of strong effective magnetic field}
significantly surpassing the external one. Surprisingly, this behaviour of the
addressed strongly out-of-equilibrium system in the vicinity of a critical
point exhibits intriguing analogy with the second-order phase transition. The
predicted field-enhancement effect can be utilized for creation of
topologically nontrivial states of Bogoliubov's excitations existing on top of
the polariton condensate.
