is far to be free kill, the sam and nin lb have huge condition that far to be a free kill.
SAM you need to use Chiten (30 sec cd), being hit by the enemy you plan to kill for place a debuff on the enemy (3 sec duration the buff, while chiten is a 5 sec duration). for be able to kill the target instantly! one important part, yes chiten reduce damage by 50%.... but you are not protected to be stunned while this, if it's happend you get your marvelous combo goes down the drain! and since you don't have diminish return... you can be stun lock while the full duration of chiten and even the duration of the debuff.... amazing free kill button!

read a skill and use it are 2 different thing... like theory and pratice are totally different...

and for one second let's remove the instant kill of the sam... what it's left to him? ogi? a 1.3 cast time in melee that have damage divide by the number of enemy hit? midare that force the use of the purify skill while having a nice cd...

i see people say sam is S tier in pvp... yes if left alone the sam is S tier... but honestly if you are focus since you will die super fast your lb will never increase and you will be pointless... because hey! even if i use meikyo i can still be stun, root or snare behind by another player.

you don't have an elusive jump like the dragoon or shukuchi of the ninja for flee... when in melee you are stuck in melee! it's either you kill or be killed!

all of this for said people learn to think before talk about what is op.... because out you have stuff far more op and no one complain about it strange... like the situation of the warrior!