regarding the auto-ability DC with the pally buff i found out this is a really really old bug, people had this issue even 3-4 years ago and the fix is to have a lot more mana, about the double of what is needed to cast the ability, so try to set up the 90-95% of MP% in the option, it seems to stop the dc
basically if you have no mana and continue to spam the ability, the game cast the spell without having the mana and it crash