I'm starting my own campaign this weekend and had questions about how the surprise aspects work in D&D 5e. I know this question has been asked before, but I have yet to see an answer describing what takes place when there are multiple attackers and defenders.
In the Lost Mines campaign, there is a goblin ambush section where EACH goblin must roll for stealth and compare it with the passive ability of the characters. As a DM, do I just arbitrarily decide which goblin attacks which character? And what if there are more goblins than characters rolling for stealth? What if multiple goblins attack one person? Or does each goblin have to have a higher stealth roll than ALL the party members passive perception? How is that all decided?