So as a stamina nb most people, if not everyone, run ambush on their bars,myself included.I had never seriously tried critical rush as my gap closer for stamina nb,but it appears critical rush would be better if not for 2 major reasons that make ambush a better choice imo.I will try to explain the pros and cons of both abilities briefly,and try to recommend which ability suits different builds.Do keep in mind this is a comparison for nightblades only,but other stamina builds of other classes can find here some valuable information.That being said,i choose to cover critical rush and not stampede,because my testing indicates that stampede never actually crits,otherwise it would deal more damage than ambush,since it was made to always crit.I may be wrong of course,but really i dont think stampede is a good morph.So,critical rush,with range from 3 to 22 meters,it is the standard gap closer for most stamina builds of other classes,it deals a decent amount of damage,(around 6700 unbuffed with my 2h sword of 3600 weapon damage) and it has a lower stamina cost than ambush,about 33 % less stamina is needed (if i am correct) to perform this ability.You cannot activate this ability within a range less than 3 meters,thus putting a stop to the close range spamming ambush receives.It can deal 68% more damage based on distance travelled,so for example if the distance between you and your enemy is 11 meters for example,it should deal 34 % more damage.Since mine deals 6700 unbuffed,a 34% increase in damage on 11 meters should make it hit more like 9000 damage.So at longer ranges,it is actually better than ambush as far as raw damage is concerned.And now ambush,my ambush of 3600 weapon damage unbuffed,deals 7700 damage,also stunning my enemy for 2 seconds in pvp,which is very very important.It has the same maximum range as critical rush,but there is no minimum range restriction,making this ability one of the most spammable in the game.It also has a certain buff,empower,that is your next attack deals 20 % more damage,no wonder people ambush and then spam wrecking blow,which also has empower as well!So damage-wised,like i said,rush can be more effective,but in pvp ,and especially ganging pvp,ambush is clearly better for 2 reasons.Number one,the animation of rush is clearly slower than the animation of ambush,it is easier for people to dodge roll,and not only is it slower,but you are visible the whole time,whereas ambush's animation is instant,and for this 1 second you cant be seen,this can make a difference between life and death while hidden and attempting to gang on 2 or 3 passing enemies unaware of your position.And it has a significantly higher stamina cost than crit rush,so even though it can be spammed,i wouldnt recommend players with low stamina pools and regeneration to spam this ability.Being an assassination ability it also gives you some of the passives of the assassination tree,most notably the increased critical weapon rate.All in all,i would say critical rush is better for players playing on a group,as it is not such a stealthy move to make,and ambush is better for solo pvp players,because of this kind of invisibility it offers you.I personally run ambush always,but in the end critical rush is without doubt a very very good gap closer.Please message me for possible mistakes i have made or things i have forgotten