Golden flash was a Force Power used to summon a blast of golden Force energy to burn an enemy to ashes. Leia Organa Solo spontaneously used this power while fighting Craitheus Qreph and Marvid Qreph to launch a blast of yellow fire that, when combined with her brother's use a half second later, burned the Qrephs to ashes, killing them and exiling the shadows that were empowering them. The backlash of the attack of the two Jedi meeting rebounded and appeared to annihilate Solo and Skywalker, though in fact they were recalled by Han Solo speaking Leia Organa Solo's name (though her body and mind appeared to be reset to 3 ABY until Han Solo explained her life, whereupon she remembered it all and aged to her proper state), then she recalled her brother when she said his name. Being subjected to the backlash of his own attack also granted Skywalker new insights into the nature of the Force.
When pursuing Craitheus Qreph, Marvid Qreph, and Savara Two into the realm accessed via the Unidentified monolith, Solo and her brother Grand Master Luke Skywalker found that the only way to slay their enemies was by using the Force to utterly destroy their bodies, as shown with Savara Two. Leia Organa Solo spontaneously discovered and used this power while fighting Craitheus Qreph and Marvid Qreph.