IIRC this is a feature from another server where a person killing the same person over and over will have a room-wide text announcement of something like "Bunny is dominating Amamin (
) with 5 kills."
If Bunny in this example is killed by another player it won't affect the kill streak he has on me, so it kind of incentivizes me to hunt Bunny to stop his streak on me, which imo adds a little bit more rivalry and fun. Putting this a step further and adding a voice notification would be cool imo, but "Dominating" is already assigned to someone indiscriminately killing 10 people (if Relax is correct) without dying so I think it should be something else.