These things are easy to tame. If you want one, go to the swamp and get out a bat (make sure there are no predators around besides the frog/beelzebufo) and then eat one stimberry to make it accessible while you’re not viewing your inventory (serves as an anti-torpor means, so take plentiful amounts and eat however many you feel needed each time the frog/beelzebufo successfully hits you as it injects torpor) and hit it until it runs away. Then chase after it and knock it unconscious and feed it some meat. And if the pink bar (torpor) is running down faster than you can collect meat for it, just add more torpor by feeding it narcoberries.
100% melee damage is 20 base damage with beelzebufo sweep attack = 60 torpor over 10 secs. A second sweep attack within that 10 secs will only deal additional damage. 1000% melee damage will do 600 torpor over 10 secs with sweep attack :)
These oversized toads are easy to tame. All you need is a bola, tranq arrows and meat to tame them. Their food drops faster than their torpor, so you won't need that much narcotics. Be careful not to tame one if there are others nearby.