Creep stacks in Dota 2 are needed so that either you or your kerry can quickly heap a large amount of gold and experience in a short time. In addition, the stack of a small camp helps to ease a light line in your direction.
How do you do the stacks?
1. Creeps appear in the camp (spawn) every minute and at the very beginning at 30 seconds, if there is no one near (including wards).
2. To make a stack you need to make creeps run after you (through a normal attack or ability) at 53-56 seconds.
3. When you return to the spawn there will be a double stack. In total, you can make up to 5-8 stacks. But the more creeps in the camp, the harder it is to do the stacks, as the creeps begin to crowd one after another.
The same scheme can stack ancient creeps. But since they stand far from the place of the farm, you can use the captured creep or ask for your support.
In the screenshots below, the kerry makes the stacks of enchants captured by creep, without being distracted from the farm on the light line.
It is especially useful to do stacks of ancient creeps for heroes who collect Dominator and have a splash attack. (Sven, Luna, Gyrocopter, etc.)