When you came up with Danger Sense were you thinking it would prevent only direct damage like Kraken and Plummeting Monorail or also indirect damage like Cramped Quarters Combat and Rooftop Combat?
Just the actual damage from things. So Cramped Quarters will still increase damage dealt by the villain when or if he hits Legacy.
Danger Sense: Legacy is immune to damage from environment cards.
Cramped Quarters: [ . . . ] Increase all damage dealt by 1.
So Cramped quarters is not dealing any damage itself, just increasing any other instances of damage. I do agree, however, that Danger Sense would be clearer if it read "immune to damage dealt by environment cards."