a few things
1) ppl who want to be grammar nazis should learn to spell "grammar"
2) no, it does not, u r wrong, it's perfectly fine as it is ("was hunted down") [no native speaker would use the phrase "was
hunt down", sorry, you lose]
3) the past tense (as in, <player> is already dead) of hunt is not hunt (and the subject of the original sentence is not the swarm, either - that's an object clause)
4) <subject> "was <verb>ed"
preposition, object clause; where, due to tense, the entire verb is considered to be "was <blank>ed" (we don't really care about the swarm; the subject of the sentence, indeed the information being passed on, is that <player> was killed - killed by what is nothing but an interesting footnote)
5) plz do moar research in future if'n u wanna b teh resident grammah not-see, kthxbai