Dawn of Fire
The Dawn of Fire is the name of an event in the Warhammer 40k timeline, taking place during the Age of the Dark Imperium. Unlike the previous narrative campaign, this one will be a combination of black library novels and games workshop rulebooks.
In real life, Dawn of Fire is releasing alongside the new Warhammer 40,000 9th edition, which is headlining the Imperium (Space Marines and possibly Sisters of Battle) vs the Necrons (as compared to 8th Edition's Space Marines vs Death Guard), so the "Dawn of Fire" could be something involving the Necrons.