Int/Dex build with Happy Break lvl 10. If you trigger Happy Break's buff, there's a chance that the ES scroll won't get consumed each time you use it. At lvl 1, it's a 90% chance to not get consumed, and it goes up to 99% at lvl 10, which is why you need lvl 10.
My memory is fuzzy on this one, but I think you have to be sitting next to a Taekwon class and do /doridori to trigger the Happy Break buff. The buff itself lasts for 30 minutes.