so a lot of people seem to not know how to properly tame a carch. you have 2 options; feed it a baby rex (which gives it full trust) or, have fun by killing tons of dinos. I prefer the second method, after that you ride it and kill a ton of creatures, and no, it's not smart to use tamed creatures, as it's faster to kill a ton of small creatures. in extinction it's extremly easy to get 100% effectiveness when taming. by the way, if it has 40% melee starting out, and if you have a giga that has 30% melee, it's mainly because if you tame anything lower than level 30 or so it doesn't have any points in melee.