The torpor will run out in about 15 seconds but the narcotics act like jerkey and last ages so if you want to tame him then prepare over a thousand narcotics and give them to him in sets of 50 and that'll give you about 8 minutes till next topup. For knockout have a fast dino ready and stand on a huge rock firing tranq arrows at him. Eventually he wi run away but set up in a place that he will run into the mountian then you can safely keep firing from behind. I did this at level 71 and damn I gotta wait till I'm level 96 to ride him.

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