As for the Summon Ghost ... if you like it, go for it !
But it's good to upgrade this skill each time you can, so your Ghost is of a good level to face the enemies and can be your compagnon for a longer time (upgrading the skill) and he heals your more(upgradign the skill) ...
Sometimes it can be the case that enemies attack your Ghost and he must defence himself, so he has no the time to heal you!!
So try to stay by your Ghost and attack those enemies that threatens your Ghost!
Mostly, when see enemies, I turn 180°, summon my Ghost (so you stay in the middle, BETWEEN enemy and Ghost), turn again 180° facing the enemies and start to attack ...
Especially in small room/dungeons this strategy is worth the effort !
I don't bother about XP ... I take mostly the extra gold or an item and not the extra XP, don't invesst in Wisdom, Mindreading ... do all mindreadings ... and at the end of Ego Draconis part (before FoV) I was L 34, almost 35. And I Keara's FF I don't spending time to do the trick with the Door that respawn enemies.
But that's ME, of course.
It's up to everyone to find the Skills etc you love most
!
