Horizon Zero Dawn offers different challenges for Aloy. The heroine will have to face and deal with stronger enemies in the Corrupted Zones.
About The Corrupted Zone
It's a place where corrupted machines live. They are far dangerous than the regular mechanical beasts. They are stronger and harder to kill but the rewards in experience are substantial.
How To Locate Corrupted Zones
The map will usually indicate the place with a red circle. Hover the pointer and it will also indicate difficulty level. As a rule, don't let Aloy go there if her experience level is lower than the challenge level. Aloy can also discover such places by her interaction with the various people she meets along the way. Tallnecks too can help locate the Corrupted Zones. A main quest, A Seeker At The Gates can help Aloy pinpoint several corrupted places.
Killing Corrupted Beasts
It seems the best way to kill the corrupted machines is by fire. This means Aloy will have to arm herself with fire weapons and load up with ammo. A stealth attack is much more preferable than direct confrontation. For these kinds of missions, the heroine will most likely wear the Nora silent hunter armor. Players should have the medium version if possible to venture into the Corrupted Zones.
It's true that the corrupted machines are more dangerous but they are killed the same way as their regular counterpart. Corrupted grazers are killed by shooting fire arrows into their canisters located at their backs. Meanwhile, corrupted watchers are killed the same way as the regular ones by shooting a fire arrow straight to its eye.
Aloy can also determine the weak spots of the corrupted machines by using a scanner. In case players encounter an unfamiliar mechanical beast, scan it first before launching an attack. A lengthier walkthrough is available here. A simple tutorial about the Cauldrons Dungeons is also available for viewing.