With the latest Hot Fix no. 5 on September 25th, respawn timers for monster caves in Skywatch, Forgotten Shore, Ember Caves, Shattered Coast and Barrens have been increased to 40 seconds, but we have a brand new farming spot for you.
Go to Patrol Cosmodrome on the Planet Earth. New farming cave is located in the second part of the Rocketyard. The path that leads to the cave is little complicated, thus, follow instructions in the video. When you reach huge trucks kill all the enemies around, that will trigger new Acolyte and Knights creatures to spawn inside the cave with a delay of 10 seconds. You can position yourself at the top of the truck or jump onto the platform left of the truck, where is much better spot to see the cave entrance.