Lately I have been interested in using this skill. I first used it as a bleed effect in PVP to counter my brothers Rend. So after I left it equipped I found its very useful in high MP.
If a target dies with this effect on, I use the increased duration for this reason, they explode dealing 50% of their max HP! That reminds me of corpse explosion. I am sure many of you have tried this already but with what results? I don't think TR monk is effect high mp so I have been trying this out.
This is what I do= Mark as many targets as I can right when 1 or 2 are about to die, and when that marked target is dead, it deals 50% of their hp which is usually over a Million damage.. Then that enemy dies and since he was also marked it basically turns into an instant type of chain reaction and they all die. So far I have had some pretty cool results, my only struggle is going against elites where it can be hard to get 1 to die while marked due to the danger and amount of hp they have, but once 1 dies with a mark, its pretty much instant NV.
The skill requires some strategic tagging especially depending on the rune you use. Now that the explosion damage is at 50% you can easily clear out mobs and elites in one fell swoop. Another tiny benefit of EP is it doesn't get cancelled by illusionist affixed elites so the tagged elite can never hide from you. A tiny disadvantage however is that EP lasts only 3 seconds on a treasure goblin (but goblins have a lot of Life and they annihilate mobs when they blow up).
There are only 3 runes worth using, these are: Flesh is Weak, Strong Spirit, and Essence Burn. The two remaining runes are IMHO worthless and should be redesigned.
Flesh is Weak makes popping the tagged target faster with the additional 12% damage. It's great against stand-alone elites and bosses. It adds another 12% to your 48% 1st 3 seconds of MoC.
Strong Spirit is great for mobs and it allows you to deplete your spirit to dangerous levels for multiple tagging. When the targets pop there is a very high chance you'll be at full Spirit.
Essence Burn is also another great mob clearer and is very economical because whatever burns will pop. It should be noted however that the explosion does not do %targetLife damage with this rune (I'm not really sure if it's a bug or intended).
On low MP, Exploding Palm is hardly worth getting, however I was really impressed with its performance when doing MP10 runs recently. Spirit is a problem, but since you usually only need to tag 2-3 enemies, it works out if you tone back on overawe spamming, and the damage output more than makes up for it, imo.