One that popped into my head instantly upon reading it was the Cold Caster feat on an Elements monk. Default to cold damage with your hits, and choose cold when using the level 6 AoE to better the chances of enemies failig the saving throw and taking the full damage instead of half.
I run for my "default" group always, but I've been lucky that one of my players also runs for his friends, and I'm included in that, and ALSO fell in as a player/GM mix roll for a group my partner became friends with.
When a person or two is going to be out of a future sesion for a group I...
I have been frequent use of that book for a few systems; very good design and usability.
I'll also echo the praise for anything written by Kelsey Dionne of The Arcane Library.
2 smashed beef patties, cheddar cheese, onions, lettuce, garam masala aoli, red pepper crema, blackened seasoning, brioche bun
Called the "Murder Burger" by a local burger/bar location.