Hi guys i will now help you tame a High level theri no sweat

1-Get 4 stone foundation,16 doorframe and 4 wooden ramps

2-build 2x2 area with foundation and put 16 ramps around them 2 block height and place ramp near it

3- find a theri and make it to run to u then run to trap let it go inside to trap

4-once it's trapped, put a sleeping bag near it that it cant reach you and sleep (it will make it's food bar 0)

4-after you sleep use tranq arrows to down it

5-you can use balm to not decrease of taming effectiveness and you can use rockcarrot to tame it faster or use mejo berries

Enjoy your therizino <3