I mostly doing stealth kill when attacking mongol camp.
My trick is use whistle to call the horse when outside mongul tent to alert the enemy after that immediately go in the tent and use "Focused Hearing" and just wait for the mongul enter the tent to assassinate one by one

i want to alert the whole camp, use wind chime only alert one enemy
i want enemy come to me...i lazy already hahaha

Want real OP then just change difficulty to Lethal and max kunai ghost weapon with equip charm that add 2 more kunai throw
Throw kunai and slash them....rinse and repeat ....that is the real easy peasy OP hahahah

More tips
Having hard time fight boss 1 vs 1 ......with this tips is easy peasy...
First, change the difficulty to "lethal", try max ur waepon as high as you can, need a lot of resolves at least more than 8 for max effect, so stock resolve first before fighting the boss. then ur need dance of wrath and heavenly strike can be obtained by completing mystic quest in act 1 and starting of act 2
When start boss fight use dance of wrath and then immediately use heavenly strike for big damage, rinse and repeat.