Fox -- who had just returned from injury -- eased alongside long-time leader Mister Coffey at the 30th and final fence to give Scotland their third win in the world's greatest steeplechase.
Fox and Russell combined with One For Arthur to win in 2017 -- he died only a few weeks ago.
Rubstic was Scotland's first winner in 1979.
"He's just a phenomenal horse," said Fox of Corach Rambler. "I can't believe it to be honest he's the cleverest horse, so intelligent, he won so easily.
"He's a marvellous horse."
Fox, 30, returned to the winners enclosure grasping the Scottish flag to be greeted with raucous cheers.
Awaiting him was Russell, her boyfriend eight-time champion jockey Peter Scudamore, and the owners, the seven-member Ramblers syndicate -- which includes 21-year-old student Cameron Sword.
Filling the minor places behind the 8/1 favourite were 20/1 shot Vanillier with the Willie Mullins-trained Gaillard Du Mesnil third.
Last year's winner Noble Yeats had looked under pressure going out onto the second circuit but ran on strongly in the final stages under Sean Bowen to take fourth.
