Warlock – “Expansion” [4th campaign, 2nd mission]

killed everyone, found all the pillars, but still can't find where the grail is buried !!!!!

I can't even determine the area from the drawing !!!!

help !!!!!

The thing is that the location of the grail is randomly generated, so no one can tell you the exact spot. During two separate walkthroughs of the mission, the grail was in different places.
The grail is indeed difficult to find using this very unremarkable riddle-map—furthermore, it's drawn from a camera angle that is impossible to achieve by available means.

Try to find some notable features on the riddle-map: the number of trees, some kind of stone. There is even a plus side to this: "Is it easy to find treasure with an old map? No, and it's just as hard here :)"
Keep looking; I think after about 15 minutes of struggle, you will find the grail.