Rune of Burning Fatality

Duration: Permanent
You place the rune of fire upon the heart of a
target creature. When they die, they explode
in a 40 ft radius sphere. Each creature in the area
makes a Dex save, taking 15d6 fire damage on a
failure or half as much on a success. If this
explosion causes the death of another creature,
they also explode and deal 10d6 fire damage in a
20 ft radius. Creatures can make another Dex
save to take half damage. Each chain of explosion
stops after the 5th explosion in th