To clarify for anyone looking for the answer to this question: Lohar has a lot of quests, and Beast will leave the party if you kill Lohar in front of him. But you CAN kill him with no negative effects if you do it right.

What happens if you kill Lohar Divinity 2?

Killing Lohar grants 5000 EXP, and his corpse has good loot in addition to the head. Bringing the head to Magister Julian yields an additional 9000 EXP and some nice (Epic) items, and closes the quest.

What happens if you kill Papa thrash?

Papa Thrash would attack you meaning you risk losing one of the easiest ways to obtain scoundrel skill books. ... If you kill him, some of the best things he sells, such as skill books and Racht Muvora armor, are available as loot.