In a manga there is a stern elf that is reprimanding his fellow adventurer for making fun of someone over drinks:
Note that there is a line break between the two halves, so it's unclear if it's two sentences or one. I'm very confused on how this あれ functions grammatically. It sounds like a conjugation of 有る, but not like the imperative form (e.g. フォースと共にあれ). Is this some other grammatical form that I'm missing?