Changes

Your eldritch blast explodes, dealing either fire or bludgeoning damage, whichever would be more damaging to each target. Additionally, any creature struck must make a fortitude save or be knocked prone, and knocked 5 ft+ 5 ft per 20 damage dealt backwards away form the origin of the damage (away from the warlock for touch attacks and cones, away from the center for bursts, and down the line for lines). Any one creature can only be forced to make a saving throw once against the knockdown and knockback effects per eldritch blast per turn; the knockback does not stack if a creature fails its initial saving throw and is struck multiple times by the blast, use the highest knockback value.