If you click on the Book Now link in the article I posted above it still takes you to the promo page. Clicking the T&C's link there brings up this:
Southeast Asia Sale Terms & ConditionsLimited availability at the discounted rates. Offer is subject to availability at all participating properties in the Hilton portfolio across South East Asia for stays booked between 13 November 2018, 16:00 SGT (13 November, 08:00 GMT) and 19 November 2018, 23:59 SGT (19 November, 15:59 GMT), and completed between 18 November 2018 and 30 June 2019. Five (5) days advance reservations required. Actual discount rate varies by property. Blackout dates may apply and vary. Rates are valid for single/double occupancy and are exclusive of all taxes, incidental charges, gratuities, and resort fees where applicable. Discount is up to 25% off Flexible Rate (“BAR”) or Bed and Breakfast Rate (B&B) across all participating properties. Hilton Honors members will receive an additional 10% off.
In addition to the room discount, there will be a 25% F&B discount for Hilton Honors members at selected F&B outlets of the participating properties during the stay:
• Discount is valid only for dinner (dine-in only)
• Discount is not valid for minibar and room service
• Discount excludes any service charges, applicable taxes and gratuities
• Discount can be used multiple times during the stay
• Discount is not applicable on Alcohol
• Discount will only be applied to the F&B bill in the guest folio upon check out
• Discount not applicable for use at 3rd party owned and operated businesses within the participating properties or if not paid for at front desk upon check out The F&B discount is not applicable at F&B outlets at the Waldorf Astoria Bangkok and Waldorf Astoria Maldives.
BAR and B&B are specific rate types that vary depending on time of purchase, are unrestricted, non-qualified and excludes discount rates. Full non-refundable prepayment required at time of booking. Your credit card will be charged immediately for the total amount quoted for the entire stay as reserved and refunds or credits will not be issued unless otherwise indicated by local law. Charges cannot be applied to other stays, services or merchandise. Booking cannot be changed. This offer may not be combined with other select promotions, offer or discounts and is not valid for existing reservations or groups. Offer components are non-transferrable or redeemable for cash, and cannot be used during future stays.
Hilton Honors™ membership, including the earning and redemption of Points is subject to Hilton Honors Terms & Conditions. All Hampton by Hilton™ hotels in Mainland China are currently excluded from the Hilton Honors program.
'+Free Wi-Fi Terms & Conditions
Hilton Honors members who book direct enjoy free standard Wi-Fi at any Hilton, Doubletree, Embassy, Waldorf, Conrad, Curio, and Canopy hotels. Free standard Wi-Fi is available for all booked stays at Hampton, Hilton Garden Inn, Homewood Suites, and Home 2 Suites. Premium Wi-Fi is available for a fee at selected properties (except Diamond Members). Not free in meeting spaces or at properties with a resort charge.