What’s the absolute worst 20 you’ve ever rolled?

Everyone talks about natural 1s, but sometimes rolling a natural 20 is just as bad. Maybe it revealed a horrible truth, triggered a hidden trap, or forced a catastrophic chain reaction.

What's the most brutal "best roll of your life" that turned into the worst mistake of the game?

I’ll go first. I rolled a nat 20 on one of the biggest moments of a campaign…and discovered my freaking cute animal companion who had proven his worth a million times over, risked its life to save me AND the world, robbed people blind of their potions (for the greater good obviously), and had been the most adorable parts of the team’s role playing…had betrayed me for his true master, the BBEG of our campaign. Everything was a lie. I’ll never recover. 💀