Yea I think this is going to be my GOTY. Here are some hints
1. Remember Knowledge is Power. Use R1 to grab orcs for interrogation. After u know who a leader is, then u can get Intel on him. Intel is the green squares on your map. Once u know their name, get the Intel to know their strengths & weaknesses. This will make each battle easier because the higher the rank, the less weaknesses they have.
I needed 7 power to level up so I went after an 8. His weakness was stealth and combo finishers. He's in the heart of his lair and he has at least 10 orcs in the vicinity. As I creep behind him for the stealth kill, I see many orcs surrounding a fire. My greed gets the best of me and I let an arrow go. They explode and the boss walks over to check. I'm then able to stealth one bodyguard, the other turns and I stealth him leaving me face to face with the boss. He goes to blow his horn, punch to the face followed by a combo finishing throat slash and a blade thru the back of his skull. Didn't deliberately level my combo it, it just happened that way. But I was in a similar situation and the captain batted away my combo. When u don't know how to defeat your adversaries, it's like throwing shit at the wall. Be Prepared.