Act 8
.. I recommend following this skill tree path which was explicitly designed to make the gaming experience as pleasant as possible for new players. That being said, it focuses more on survivability and comfort than damage, but the guide will elaborate on options to adjust the skill tree in order to be more damage centric later.
For now, this is optional. You can do this later as well. Trials of Ascendancy are mazes within specific areas of the campaign – in this case, The Bath House.