A hot stable field-reversed configuration (FRC) has been produced in the C-2 experiment by colliding and merging two high-beta plasmoids preformed by the dynamic version of field-reversed theta-pinch technology. The merging process exhibits the highest poloidal flux amplification obtained in a magnetic confinement system (over tenfold increase). Most of the kinetic energy is converted into thermal energy with total temperature (T(i) + T(e)) exceeding 0.5 keV. The final FRC state exhibits a record FRC lifetime with flux confinement approaching classical values. These findings should have significant implications for fusion research and the physics of magnetic reconnection.