When exactly will part 2 of the summer event be avaliable?

August 6th according what I heard.

Augustus 6, and it goes until day 14.

Also, looking at the wiki, is going to be more difficult, as the nodes have so much mixed teams of enemies classes (specially if you want to max those bonuses drops).

At least we get a fixed node to farm hearts during the event, and there are a total of 20 pages to buy in the shop...

The news in the game says 6th August.