If you use a Maybank card, CheapTickets.sg is offering $20 off flights to any destination. Use coupon code MAYBANK20 when you book your flight.
Discount code: MAYBANK20. Book before 31 December 2018
However not budget airlines. From terms and conditions:
Not valid on budget/low cost airlines including but not limited to (AirAsia, ThaiAirAsia, Tiger Airways, Cebu Pacific, Jetstar and Scoot).