by johnnythac0
Oh wow, so reading it again carefully it is WHILE your sanity is on (or one back). So Adam gains an extra dice while on the 1st insanity threshold (other investigators do not), and at 2nd (or space before), then potentially two total extra on the third and then potentially 3 extra dice on the final three thresholds.So he’s be rolling the 3 extra and 2 more if he is attacking in the adjacent space and has marksman level 1.
I think I may have answered my own question, but was helpful to write it out. :)