Advise for BG3

So I made my 3rd cleric now in the game this time one of Knowledge and chose Mystra. Can anyone give me help how to build my spells and if there are any special dialouge for that deity? I finished the game twice now with two clerics and I can’t get enough of that class since it varies with the Domain you pick. Thanks in advance for anyone stumbling in here.

This feels like a good opportunity to multi-class wizard, no?

Gale is wizard and Shar is not pickable for playable clerics. My original main was a sorcerer but I missed too many sidequests so I restarted.

You might get some dialogue with Gale, maybe. With the whole Mystra thingy.
Just hide behind Karlach. Like most clerics, its either cc enemies or buff allies.

Skill bonues help with dialogues for some npc interactions. Like religion or arcane for example, I think Knowledge gets as a choice. You’ll never get all options of course.