insidiously (adverb)

1. In Greek mythology, the god Apollo insidiously tricked King Midas into making a wish that turned everything he touched into gold.

2. In the novel, the villain insidiously manipulated the protagonist's thoughts and actions, leading to his downfall.

3. During World War II, Nazi Germany insidiously implemented propaganda campaigns to control the thoughts and opinions of their citizens.

4. The supervillain disguised himself as a hero and insidiously infiltrated the group of superheroes, aiming to betray them from within.