Singularity

Kill 15 people with the Lurker's Shield Power. This one is tricky because most people know not to hit a shielded player. If anybody hits you with melee they take damage. You will get the random newbie once in a while who will still hit you and not know why he keeps dying. But that's if your lucky the only enemies I got to actually come up and melee me were Zeks. (EDIT: Once a Revert/Zek player has hit the melee button twice, he can't stop his attack. Giving you an easy kill.) Just make sure you don't hold it down for a long time. Just get up in their face and then tap it when you think they are gonna melee you.

This accumulates over time, the easiest way to do this is have someone be a Phase tick try to attack you when your use your shield. you will get an instant kill on a phase tick.

This doesn't have to be done in one match. It'll accumlate over matches, every time ya get a sheild kill. (Now to make this 25 words long.) Best strategy I can suggest is to sort of just get the attention of any enemy with a melee attack and have them come to you, sort of bait yourself. When you can tell they're gonna lay the beat down, simply use the sheild and deny them of that opportunity.