Ral Zarek and Hekara activated the Interplanar Beacon to call planeswalkers to Ravnica as reinforcements against Nicol Bolas. The activation was an act of resistance, but it also served Bolas's larger trap: newly arriving planeswalkers could not leave while the Immortal Sun remained active. The summoned allies arrived separately, unaware that the very spark that let them answer the call made them prey.
The trap turned a city-plane into a closed battlefield. Experienced heroes, opportunists and walkers with no connection to the Gatewatch suddenly faced the same threat. Some possessed extraordinary magic, but none had prepared for a war in which every spark made its owner valuable prey.
For Ravnica's residents, the invasion was not an abstract contest among cosmic figures. Streets, homes and guild territory became front lines. The people most likely to die had never chosen to enter Bolas's game, which gave the visiting planeswalkers a responsibility extending far beyond their own survival.