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Several redback and black widow millisecond pulsar binaries have episodes offlaring in X-rays and optical. We initially detected such behavior from theFermi selected redback candidate 1FGL J0523.5$-$2529 during optical time-seriesmonitoring. Triggered observations with the Neil Gehrels Swift Observatory overthe next $\approx100$ days showed episodic flaring in X-rays with luminosity upto $8\times10^{33}$ erg s$^{-1}$ ($\sim100$ times the minimum), and acomparable luminosity in the optical/UV, with similar power-law spectra of$f_{\nu}\propto\nu^{-0.7}$. These are the most luminous flares seen in anynon-accreting "spider" pulsar system, which may be related to the large size ofthe companion through the fraction of the pulsar wind that it or its ablatedwind intercepts. Simultaneously with an optical flare, we see Balmer-line andHe I emission, not previously known in this object, which is evidence of astellar wind that may also inhibit detection of radio pulsations. The quiescentoptical light curves, while dominated by ellipsoidal modulation, show evidenceof variable non-uniform temperature that could be due either to large starspotsor asymmetric heating of the companion by the pulsar. This may explain aprevious measurement of unusual non-zero orbital eccentricity as,alternatively, distortion of the radial-velocity curve by the surfacetemperature distribution of the large companion.

Luminous Optical and X-ray Flaring of the Putative Redback Millisecond Pulsar 1FGL J0523.5$-$2529