The Soloist
Hero
Play the Mortal Combat song for the players. With my group it works evertime. They start rolling high again. 

I think the 13th Age 2e Playtest part of OP's post is pretty coincidental. OP could've said "DnD5e," the differences aren't huge as far as them both being d20 fantasy games, though 13th Age wears its heroism on its sleeve.Maybe you got a good feel for the game, then? Time to move on, or are you committed to 13'A_2e>pT for some reason?
Usually I'll acknowledge their bad luck in a lighthearted way. "Damn, you've got the worst luck tonight." It happens to us poor, trodden DMs as well. Just last week I rolled the minimum damage against player characters three times in a row. I was so sad.I'm wondering if my fellow DM's have any ideas/advice to help when players are feeling bad about a game due to streaks of bad luck?
I don't think it helps them, but I can't help but sympathize with them audibly/visually... maybe it'd be better instead to be the eternal optimist, "oh hey I'm sure a good die roll is right around the corner!"Usually I'll acknowledge their bad luck in a lighthearted way. "Damn, you've got the worst luck tonight." It happens to us poor, trodden DMs as well. Just last week I rolled the minimum damage against player characters three times in a row. I was so sad.
Even as a player, I don't usually get bummed out when I'm rolling poorly all night. I just laugh and laugh. I just don't take D&D very seriously whether I'm a player or the DM.I don't think it helps them, but I can't help but sympathize with them audibly/visually... maybe it'd be better instead to be the eternal optimist, "oh hey I'm sure a good die roll is right around the corner!"
Same - I like to role-play failures; the more spectacular the better. I live for natural 1s!Even as a player, I don't usually get bummed out when I'm rolling poorly all night. I just laugh and laugh. I just don't take D&D very seriously whether I'm a player or the DM.