Pro tip: Don't use explosive weaponry and really bad rexes with no saddles like the devs did. Fab Snipers for taming it with little/no collateral damage, actually decent rexes + imprint + saddles to kill it
Try to hit the coropted glowing things around his body. Ice you have destroyed all, it should fall down on the ground knocked out. You do not need any taming food for it, Just go up to it and click tame to tame it. No need to build a saddle because it already comes with one.
Just use tek armor and have a shot gun or rifle with a whole lot of ammo like 1000 and medical brews. Stay high cause it CAN’T fly and it’s vine attack only shoots forward. If you want, you can use some stuff to tank or bait it like a friend in a mek.