Invisible Abilities

Avoid abilities that do nothing but change the creature's math, also known as “invisible abilities.” These alter a creature's statistics in a way that's invisible to the players, which makes the creature less engaging because the players don't see it using its abilities in a tangible or evocative way. For example, an ability that allows a creature to use an action to increase its accuracy for the round with no outward sign (or worse, just grants a passive bonus to its accuracy) isn't that compelling, whereas one that increases its damage by turning its machine gun bullets into superheated plasma is noticeable. These both work toward the same goal—dealing more damage this round—but one is far more memorable.