Encounters that didn't work

[Eurus]

I made a big scary sphinx monster as a boss, and it got the worst rolls I've ever seen in an encounter. It was hilarious, but also felt like a bunch of wasted effort. All these cool abilities and attacks I designed for it, and the thing just could not roll above a 5. A humbling reminder of the chaos of existence, and also the value of a good DM screen to roll behind.