I just reached the beginning of Act two. In the Ossean Wastes, you will find Dune Mothers. They spawn little scarabs, and as long as you don't kill the Dune Mother, she will continue spawning the scarabs indefinitely as far as I can tell. The problem is that the Dune Mother is super fragile. I tried taking her down to half health, traveling to the previous town and back, but she still maintained the same half health level I left her with. So, the strategy is to place your pet on passive so it doesn't attack the dune mother (keep it passive the entire time to minimize risk of the dune mother coming near and accidentally be hit by your pet), run near the dune mother to trigger her summon of scarabs, and lead the scarabs away from her. I personally use the Prismatic Bolts because it's pretty powerful, has quick casting/recharge time, and strikes multiple opponents at once, which is important because the further you run from the dune mother, and quicker you outpace the scarabs, the more that will turn back towards the dune mother. Prismatic bolts will help engage large numbers at the same time, and damaging them aggro's them, insuring they continue to pursue and assault you.