NARS currently has 30% off sale items as the lead offer on this page, and that is best for you if your cart is mainly sale products you already planned to buy. The 30% off sale items is site only and cannot be used with any other offers, so it suits shoppers who will fill their basket with marked down items. If your cart mixes full price items or you are chasing gifts with purchase, one of the other deals may be a better fit.
For large sale only baskets: If all the items in your cart are on sale, use the 30% off sale items. For example, on a C$120 order of sale products, the 30% discount takes C$36 off, leaving C$84 at checkout. This is a straight percent off sale prices and, per the terms, cannot be combined with other offers.
For shoppers spending CA$90 or more: The free mini Multiple and mini bronzer requires a spend over $90. If your basket totals $91 or more and those free items are what you want, that offer applies, but note its terms also say it cannot be used with any other offers. If your $91 cart is mostly full price products not eligible for the 30% sale reduction, the gift can be more useful than a sale percent you cannot apply.
For carts of CA$85 to CA$89.99: Spend CA$85 or more to get the free mini blush and light reflecting setting powder. This gift with purchase activates at CA$85, so a CA$86 basket that would not qualify for the $90 gift still gets value from the CA$85 deal. The free items do not lower your order total, they add product value.
If you are buying bundles: Bundles marked down under the 20% off bundles offer get 20% off. That is specifically for bundles and for sale products only; if you already have a bundle in your cart, apply that 20% saving rather than trying to use the 30% sale offer, since the 30% offer cannot be combined with other offers.
If your purchase includes mascara or liquid eyeshadow: Buying either of those product types triggers the free Nars hairclip while stocks last. That is useful if the clip matters more to you than the other available gifts.
When choosing between these options, calculate the final price for the same basket under each applicable offer and pick the one that leaves the lower total. Remember the 30% off sale items and the free mini Multiple and mini bronzer both state they cannot be used with any other offers, so you must choose one primary offer at checkout. If you are unsure, compare the numeric total after the percent discount against the price you actually pay when a gift applies, and take whichever gives the lower outlay.