As mentioned above, I got about 31% of the achievement progress done just on one map. This meant that I didn't need to kill an enemy to get a corpse, I could spawn one myself first. This essentially teleports the character away from the enemies but also leaves a body that you can explode.

I also had 'Blood Rush' with the 'Molting' rune. I toyed around with 'Bloody Mess' (increase explosion radius) and 'Shrapnel' (explode away from character), but found that the 'Dead Cold' rune meant that the undead enemies that hadn't died would freeze meaning they couldn't move. Skills For skills, I had 'Corpse Explosion' (of course, since it's required) with the 'Dead Cold' rune. I also ensured I checked the corners of the map, as it will always spawn about 5 undead enemies per corner. I also did one with the 'Grave Robert' bounty and it gave good results too.

Map I stuck with the 'Briarthorn Cemetery' area in Act 5, mostly because Cemetery = undead, right? I also reloaded the map a few times to get the 'Rathma's Gift' bounty, as I think it has the highest chance of spawning undead enemies. I was able to get from 65% to 96% using this method, all on one map. I was able to complete this pretty quickly by following the below.

Diablo 3 reaper of souls necromancer