Just got a frenzy today that's five straight which is my personal best.
I figured you'd get them all and unlock a ton of xp. Thanks for the heads up. I suppose this makes sense because when you get a triple kill the game doesn't award you the triple kill medal until the chain times out and you do not get a double kill medal on top of it.
Congrats. I was somehow able to get both the Chain and Ultra Killer challenges done in the same game. Shortly after I was able to finish off the Quad Feed challenges to finally get the Master Killer title.
Both of the Chain and Ultra Killer I was able to get done on Plaza in Domination. I went over to the D'BO side of the map and rushed their spawn towards C Domination. I got the Ultra Killer in the first round and the Chain Killer in the second round.