Tallnecks are very large Machines that kind of resemble giraffes of sorts, with a large antenna for a head. These machines can be climbed by jumping from a nearby area and onto their necks. Once you reach the top of them, you’ll be able to thrust your spear into their heads, which will reveal a portion of the map for you, highlighting any points of interest. Anytime you get close enough to one, you will hear Aloy mention a strange signal and if you look around with your Focus, you should spot a pulsating purple signal that will put the Tallneck into your quest log if you scan it. All overridden Tallnecks will not only reveal a section of the map, but you will also receive 7,500 XP and a Skill Point.
Tallneck - Devils Thirst
While heading north for A Seeker at the Gates, you will see Aloy mention a strange signal. Look to the northwest with your Focus activated to see a pulsating purple signal. Scan this and you will activate a sidequest to investigate the signal. Once you get close enough, you will see, and hear, the monstrosity that are Tallnecks walking. You can’t damage it and it won’t attack you, so do the next best thing, climb to the top and stick your spear into its head.
The building it is walking around (beware of Watchers) has a ledge at the top that you can use to get a running jump to grab one of the things sticking out of its neck when it passes. You can then leap from platform to platform until you get to the top, where you will get a prompt to Override the Tallneck. Doing this will reveal a good portion of the map, as well as receive a Skill Point and a hefty XP bonus.
Tallneck - Sun-Steps
You will find this Tallneck northwest of Daytower and when you arrive, there will be a plethora of cultist human enemies. In order to get to the spot where you can jump onto the Tallneck, you will have to fight through some, but not all, of the cultists. There is also a Corruptor in the middle of the camp, but you shouldn’t have to worry about, although there is a quick way to take it down. Start from the campfire to the south of the Tallneck, where you can pick off a few cultists.
There will be a ramp to the east of the wooden walkway you might see from the previously mentioned campfire. Go up this ramp and follow the way to the west to fight more cultists, including an elite with a Deathbringer Gun. The first thing you should do with this is take down the Corruptor to mitigate any chance of it attacking you. Depending on how much ammunition you have left, use it on the other cultists. In the area just past the elite is a wooden platform jutting out a bit, which is where you will be jumping onto the Tallneck. Climb to the top, override the beast and you’re done with this one.
Tallneck - Copper Deeps
West of Cauldron Rho or southwest of Daytower is where you will find this Tallneck and it is potentially the most difficult to reach. There are two islands in the middle of this lake, with a number of Watchers and Snapmaws patrolling the area. The southeastern ledge on either island will allow you to reach the Tallneck. With that knowledge, you have one of two approaches here, with the first one to sneak your way past all of the enemies and just jump onto the Tallneck.
The other option is to wipe out the machines on one of the islands, or both, noting that the Watchers can’t cross the waters. This means the Snapmaws will be your biggest threat, but their weakness to fire makes them easy targets, especially if you remove the armor on their Blaze Canisters. Whichever method you choose, jump onto the Tallneck, climb to the top and override it to finish.
Tallneck - Spearshafts
Northeast of Cauldron Xi will be this Tallneck roaming on a circular path rife with Longlegs, a few Redeye Watchers and some Sawtooths also close by. You might have to dispatch a Watcher and/or a Longleg or two, but you don’t need to kill every single machine. If you look at the circular path on your map and zoom all the way in, you should notice what looks like a ledge on the southern side. That is the ledge you want, as you can jump onto the Tallneck from there. Once you get to the top, override the machine to finish with this one.
Tallneck - Rustwash
This Tallneck is located south of Sunfall, which is on the western edge of the map. If you haven’t gotten that far yet, you will find the Tallneck pretty much in the middle part of the western edge. There are a number of enemies in the area, including a few Watchers, Redeye Watchers, Longlegs, Ravagers and even some Fire Bellowbacks. If you feel threatened at all, one of the easiest ways to take out all of the enemies is to shoot off the cannon on the Ravagers, then use that to decimate everything.
Southwest of the Tallneck icon on the map will be a rock formation with some debris forming a platform that sticks out at the top. Jump onto the Tallneck once it passes around, then climb your way to the top, where you can override it. Enjoy your experience, uncovered map and new skill point.