Virulent Walking Bomb

The caster sends a beam of necrotic entropy to a target you choose within range, it then infects the creature with explosive necrotic energy. The targeted creature must make a Constitution saving throw. On a failed save, the creature takes 5d6 necrotic damage and another 1d6 necrotic damage at the end of its turns. If it dies, any creature within 15 feet of the target must make a Dexterity saving throw. On a failed save, a creature takes 4d6 necrotic damage or half as must on a successful one. On a successful save, it takes half the initial damage, none at the end of its turns, and the creature also does not explode when it dies.

After the target dies, any creature that was in the the 15-foot radius must make a Constitution saving throw. On a failed save, the creature is under the effect of the Walking Bomb spell (seen in homebrew). The Walking Bomb spell is cast at 2nd level.

At the end of each of the creatures turns, it can make a Constitution saving throw against the spell. On a success the spell ends.

At Higher Levels. When you cast this spell slot of 5th level or higher, the initial damage increases by 2d6 for each slot level above 5th. The explosive damage increases by an additional 2d6. If the spell is cast with a spell slot of 8th or higher, any creature is effected by the initial explosion is now under the effect of Virulent Walking Bomb instead of the stranded Walking Bomb spell.