Between Oct 4 to Oct 10, 2018, you can get 10% off when you buy Air Canada Gift Cards in some grocery stores, such as Sobeys, Safeway etc... I suggest that you can use AmEx Cobalt Card (or other credit card with high return on grocery stores) to get 5X points on the gift card purchase. Totally, it is equal to ~15% off on Air Canada gift cards, which is quite good if you plan to take their flights in the near future.
BTW, Air Canada Thanksgiving Sale is ongoing right now until Oct 9, 2018. I should say that it is just good timing to buy some Air Canada gift cards.
