I played from both sides and can tell you vanish has its purpose but it also has its cheapness, But some of use came up with a decent solution.
Purpose: You 1v1 someone, then someone else adds on you and you are now at a great disadvantage of 2v1
Purpose: You kill an enemy in 1v1 but before you can stealth an 8man rolls up on you...
Cheapness: You start a 1v1 fight, then vanish because your target isn't an easy kill.
Solution: There are 2 separate requirements that only one of must be met for vanish to be useable.
(1) You can only use vanish if 2 or more enemies are currently attacking you.
(2) An enemy target that you did damage to has died in the last 10 seconds.
Purpose: You 1v1 someone, then someone else adds on you and you are now at a great disadvantage of 2v1
Purpose: You kill an enemy in 1v1 but before you can stealth an 8man rolls up on you...
Cheapness: You start a 1v1 fight, then vanish because your target isn't an easy kill.
Solution: There are 2 separate requirements that only one of must be met for vanish to be useable.
(1) You can only use vanish if 2 or more enemies are currently attacking you.
(2) An enemy target that you did damage to has died in the last 10 seconds.