The Rock Touch

Anyone/Anything throws/hits you with a rock. Roll 1d100 and if it rolls 1 the rock is enchanted with an aura that you can pick up and throw at anything. What you throw it at will automatically take the rock's aura and kill anything that touches it instantly and becomes void. The rock's void aura won't grow or do anything until it is thrown by the character who cast this spell. 

If your character is level 10+ the item that gets hit by the rock also spreads its void aura with any solid/liquid touching growing a 1-millimeter greater radius in every way (length, width, and depth) per cubic foot corrupted per second. The void aura will also grow tentacles coming out of it after it reaches 100 cubic feet.

The only way to reverse this cantrip is by the player who cast this using Eldritch Blast with 4 beams on the aura and it will reverse at 1-millimeter per second.