Just a tip: sometimes the Raptors spawn in such a way, that you can aggro the whole cave, and run back to the cave entrance... without spending any extra time. The Raptor patrol outside the cave will arrive at about the same time... meaning extra kills for free.
Screenshot below shows 39 kills instead of the usual 33 for an E/Me. That's just from the normal 1 cast of Sliver armor, plus a single recast after the boss dies. (I have max or very high ranks for my PvE skills though - ymmv).
You should aggro the cave, get back to the entrance, and begin the Mist Form / Sliver killing sequence within about 45-50 seconds of starting the run... otherwise the patrol will have already passed by the entrance. If you can't do that... you're probably not reaching the cave fast enough: make sure you assign shortcut keys to cast hero skills, target yourself, and bring up the hero's flag.
It's down to the luck of the spawn, but it's do-able fairly frequently - so it's worth looking out for.
R


