I tried the triangle formation of metal dino gates as per one of the top tips but that didn't work. What did work for me was a four wall box of stone behemoth gates and then kiting the rex into there with a flyer and then closing the rex inside. Make sure you placed the gate box near a high boulder so that you can land there and tranq the rex from above.

On mobile:

30 tranq arrows’ all it took to knock this guy down. (Used crossbow) even less if you aim for the head.

-Have at least 1 or 2 prime meat

(kill a nearby carno/sacro/boa)

-And at least 25 regular meat.

-In like 2 in game days youl have this guy

Sleep and leave this guy alone. He wont be eaten whilst unconscious by anybody.

Ps: Im by no means a pro, I only speak by experience. It’s THAT easy. Maybe theres an easier way but i find this method the easiest.

If you see one, and are trying to fight or knock it out, i recommend going to a ledge above the rex, which in where it spawns can happen, make sure to use a good level longneck or other powerful tool if you want to kill one, and relocate if it gets close (they are not too fast). To knock one i recommend tranq arrows or darts (arrows if you have a good crossbow, they cheaper) and if you knock it just feed it prime meat or mutton, wait and then you get a Rex. If you have a tame that can outrun it you could relocate much easier

Rex is an easy tame if you can get a beezlebufo the gaint frog just hit and run with tranqs while on the frog rex will never be able to touch the frog coz you'll be able to jump real far and shoot the tranq when the rex get close jump again to keep distance then shoot the rex to sleep by continuing the process the frog can be used to tame almost any creature whether land or water

The safest way to find and tame a rex is to go to the winte- south zone 2 "alley" with the river that intersects into a swamp and another river that eventually goes to green ob

If you are playing casually and you pass through this area a lot one should spawn because it isn't rare for them to spawn here.

If you find a rex and it sees you it will start to prioritize you for a moment but if you have enough tranqs and movement speed you can run far enough away from it so that it will attack something else instead, then you can tranq while it is attacking the other creature.

If you don't you can just use a pternadon or anything thats faster than a trex then just dismount to tranq.

After you knocked it out you can get prime meat from stegos, diplos, or carnos that spawn in this area.

Easy process to find a tek rex on the island in UME:

1. Go to carnivore island

2. Bring a strong tame that can decimate every creature there (i usually bring a carcharo cuz it can 1 shot almost every creature there)

3. Kill any raptor, sabertooth, carno, argy, and rex that spawns there and continue for as long as you can until you see a shiny, metallic rex that looks robotic

4. If you're on singleplayer, then here are some bonus tips:

4a. I recommend backing up a save file every time you see a supply crate reach the ground since every time you enter your game a supply crate will be guaranteed to spawn near you shortly after. (You can also use this to farm keys since you wont need fo fly miles at a time to check every supply crate since if you're at carno island every supply crate that spawns WILL ALWAYS be on carno island unless you leave) If you can't kill everything on carno island once before the first supply crate reaches the ground, then back up a save every time you kill a rex or 2.

4b. If you find an alpha raptor, carno or rex and you need better gear you can back up your save and then kill the alpha to have a chance to get hide armor, sickles, pikes, metal axes, metal picks, crossbows, bows, and finally simple pistols (sorry this doesnt include swords). Chitin armor can also drop from alpha carnos and alpha rexes, and when paired with a high enough difficulty level and good enough luck, you can get a mastercraft or ascendant piece of chitin armor that can be stronger than a primitive flak piece (100 armor)

If your looking for a good level rec trust me it all DEPENDS ON YOUR LUCK I've been looking for a max level rex for alpha boss fights and I keep finding shitty rexes the highest I encountered were 125 and lvl 100 on beaches . I also found a 145 when I had no tranqs and when I came back it despawned . Just remember if you need an boss fighting army you need a rex army with good stats noy just levels

BOSS REX’s

For gamma bosses I recommend:

Hp 10K

Md 600

With 50 armor saddles.

For beta bosses I recommend:

Hp 15K

Md 1.2K

With 80 armor saddles.

For alpha bosses I recommend:

Hp 35K

Md 2K

With 120 armor saddles.

Buff your rexes with a yuty and optionally heal them with a pig. 100% imprint provides 30% more damage given and damage negation when the imprinted rider is riding.

I don’t recommend rexes for bosses that deal fire damage as carnivores take increased damage from it.

All of these estimations are assuming you are solo on official rates, the more people in the fight the lower the rex stats are required to be.

Many of the people here are saying to just go and shoot them. Just do it. I would agree. When if tamed mine I was scared that it was to fast, but you can easily beat it while sprinting. shoot it, run away, repeat. easy. Tranq arrows will work fine just bring enough. And be prepared to make more just incase.