Thermonuclear Warhead

When casting, point at an area within line of sight. A thermonuclear detonation will occur dealing damage to everything within a 1000 foot radius. If a creature is within 50 feet of the center then it is instantly destroyed. No saves are possible and a damage roll is not needed. If a creature is between 50 and 150 feet of the epicenter, roll 20d20 for damage with a save reducing damage by half. Between 150 and 400 feet roll 12d20 for damage with a save reducing damage by half. Between 400 and 800 feet roll 5d20 for damage with a save reducing damage by half. Between 800 and 1000 feet roll 1d20 for damage with a save negating damage entirely. HOWEVER, any target within the various distances from the epicenter suffers 5d10,  4d10, 3d10, 2d10, 1d10 poison damage respectively.