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.
Enable Raid Dino Feeding in settings to keep the Titans! This guy is my fav though, you can legit just chill on his back like you would in a regular jungle but no Troodons to just obliterate you and your mood