Up to 17% cashback at Myer begins at 10am AEDT and ends at 2pm AEDT.
Can't see further details on what category get the 17%, but I believe it'd be a repeat of this deal:
https://www.ozbargain.com.au/node/752402
As per previous deal above, there's also Westpac $15 bonus for the whole day:
$15 bonus Cashback when you spend a minimum of $50 in a single transaction at Myer (excluding delivery and all other fees) with your eligible Westpac card. Limited to 1 transaction per customer.
CBA card holders might also be eligible for $10 back when you spend $100+ at Myer till 29 March. Activate the reward in your Commbank app.