Presentation of General Temuge
It won't be your first fight against one you come across in Ghost of Tsushima, but it could be the most difficult at this point in the game. General Temuge is quick and armored, and can easily exhaust your resolve, leaving you open to battle. dead. However, this fight plays out similarly to other fights in that you have to dodge the red attacks of this enemy. Use standard dodge and counter attacks when attacking with unblockable moves. Although this boss throws some wrench into the situation with a flaming sword that can set you on fire.
What you need to know here is that whenever he has a flaming sword he will attack you with an unblockable red attack. You will get one of a short list of moves on these attacks. This will likely be either a two or three hit combo. Press the circle button to avoid these attacks and if you attack immediately after the last hit of the combo you can hit it, otherwise it will block the attack if it is too late.
General Temuge Boss fight video
Once the sword's flame goes out (which you can hear by the sound of the steam if you can't visibly notice it), try using a regular block / parry combo that will allow you to hit it. There are several important steps to take down this boss which will be marked by vocal exchanges between the two characters.
Just follow this path to victory. Get small hits on the dodges between red attacks. When the flame goes out, wait for a standard block / parry / counter to finish it.