Unstable Equilibrium. Some of it is good, too much of it is bad.
Having good players stay invisible while punishing bad players by making them visible
would make it so eventually one or two people would have tons of kills and no deaths.
Currently the biggest offender in that this aspect of game balance is the vampire mutator,
that's why most people combine it with resize so when a giant walks into a
room almost everyone immediately focuses their attention on that person.
That gives me an idea though...
[insert cool name here] mutator (default settings): every time you die you have 10 hp added to your max hp, and 10 hp subtracted from the max health of the person who killed you.
Upper max hp limit is 200, lower max hp limit is 10. If one person is already at their max/min when a kill is made and can't go any further up/down, then no hp is traded.
Death by grunts, turrets, falling, and hazards never will deduct health from someone who is killed by them.
If a player leaves in the middle of a match, the next person/bot that joins inherits their hp total.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Example:

and

are playing
[insert cool name here] duel on
dutility.

is awesome,

is a n00b.

will kill

much more often then

will kill

.
Eventually this results in
not having very much health at all, while

will have
a lot of health.
This makes it
easier for

to kill

, and
harder for

to kill

.
In large battles hp will be traded back and forth
often between multiple players.
It may, however,
disrupt balance by making some
weapons less popular in the
[insert cool name here] mutator, such as the
rocket,
since a well aimed shot could kill 3-5 players at once, thus
depleting a player's health by
30-50 points.

Also, this mutator might also produce interesting results when combined with
res
ize.