Hunter (Mercenary) has a clause in his first unique where he gains a bonus turn whenever Marked expires on an enemy if he has 15 or more stacks of Target Practice, however this bonus doesn't trigger if the enemy that is marked is killed.
The screenshots below depict an enemy that is Marked while Hunter has low Turn Meter and 15 stacks of Target Practice. When the enemy is killed, Hunter does not gain a bonus turn despite the enemy being killed, thus causing Marked to expire.
