<p>In my opinion the best place are<strong> Zao Steppes</strong>, just throw some fire bombs in places where you see groups of them.</p><p>+ Little suggestion - if you kill Grand Master Oberon everyday, skip Sandcrawlers during rapid respawn weekend Rapid Respawn Weekend and simply kill it on your way to Oberon (in case if you don't care about your Stamina).</p>