acid blood

You draw your own blood, sacrificing a bit of your life to create a explosive fountain of acidic blood. You hit yourself with your weapon, then each creature in a 15-foot-radius sphere centered on a point your designate must make a Constitution saving throw. A target takes [roll]4d4[/roll] acid damage and [roll]4d4[/roll] necrotic damage on a failed save and is poisoned for 1 minute, or only takes the acid damage on a successful one and is not poisoned.