* Using Stealth Attack will no longer cost a Soul Fragment or trigger the cooldown of Miasma: Face Stab, but the Stealth Attack will still perform the Miasma: Face Stab ability in addition to the Stealth Attack.
from the 1.06 patch...very odd didn't see this before - seems a good way for Sins to get some extra dps from an initial stealth hit...
See, I'm a newb Sin
Tbh had no idea about this (baaad adviser

) - Next time I steal aggro at Chatha pls blame Funcom (I am not a newb sin...just a n00b one

)
2) any good levelling build to learn the mechanics of the Miasma side of things?
Imho there is no such thing...the only way is "spend some points on them, put them to the test and you will learn what you need to know"...
The basics tho are here
MiasmasFace stab (piercing dmg):use it right before the combo finisher, use it after one or both base poisons are applied, combine it with your debuffs and the other miasmas(for example burden to bear if feated gives: physical torment, grim corruption: gives spiritual and physical wrack, detonation gives: spritual and physical wrack, spiritual torment

)....in other words use it when you want to finish off your enemy or/and boost you dmg...it's fast,it's clean,it's safe

Soul Strike: Do not hesitate to use it as stun when you deal with multiple mobs.Detonation by its own can't make your life easier in large pulls, even if its crits are insane (they are indeed)... Those 4secs of delay can make the difference and kill you at the end ...
Dart: cc you enemy, apply the dot and focus on the rest

- [80lvl: not useful in pvp (lots of HoTs out there unless you have tw

), in pve can be less aggro friendly]...
Leveling: What you need is fast kills...So focus on your dmg output. You can play safe by having both dps and enough cc's ...Miasmas: Get them all, try them all (necrosis and unholy stabs is a must to have)
Wtr our conversation about Stealth and Face Stab:
I strongly believe that this dmg boost can't make the difference... not in raid instances, given that you can't use hide mode there(good to know tho).Unless ofc 23 ppl sheathe their weapons and make a short (long same difference ) pause.If what you are looking for as sin is "moar damage"...most important is, your combo rotation,your position,your movement (open your combo and follow your target/or go to the next one...sit still only for the finisher...just keep moving, keep hitting, pop your miasmas at the right time - just before the end of your poison's effects, boost your combo's dmg with debuffs etc,etc

)