Sha of Anger kill trick

I've witnessed a pug group on Jaedenar kill Sha of Anger almost 1 shot, boss was on 80-90% hp and suddenly died. This happened maybe 10 hours ago.

Did a little digging and found out that it was done using a bugged mechanic from a ret paladin. On 80% the paladin casts Execution Sentence and the final tick does enough damage to kill the boss 1 shot. I've not tried it yet and would hope to get some info from people that know about this/did this. 

Apparently the guys from Loot FTW used this tactic first on live servers and someone linked in chat a bit of their recount showing one of their paladins doing 226 milion damage on that particular spell.