In the "Gorinych" mission, if you can't handle the squares, here's the shortest path: 1) 1 time, the lower-left monk (south-west); 2) 3 times, the upper-right monk (north-east); 3) 3 times, the lower-right monk (south-east).
Regarding the tree. First, you need to find the red monk (in the eastern part of the map, not far from the "town" where the Sanctuary is), defeat him (answer YES to the question), and then go to the monk nearby and perform a "good deed." Capture the Necropolis, then go to the Necromancer, defeat him, and destroy the town (for this, you need at least 1500 ghosts, and preferably closer to 2000), after which you return to the monk and talk to him. And that's it, the mission is completed.
I have a question about the next mission, which is called "In the Wake of Gods." Besides me, there are three other heroes who are locked up. So, I visit the "mushrooms," lose experience while freeing these heroes, then teleport somewhere through the fountain, and wander around. And then I don't know what to do.