Apocalypse by J Robert King (Magic the Gathering Invasion Cycle #3)

The end is near! Phyrexian plagues and shock troops have taken their toll. The final stage of the invasion has begun, and the dark lord Yawgmoth himself plans to cross over into Dominaria to claim his prize. With time running out, the battered heroes' last hope to save their home lies in an ancient, untested weapon—a collection of artifacts known as the Legacy. Bear witness to the apocalypse.