It's not strictly speaking a 100,000 miles bonus, but it's still a way to pick up miles for cheap...assuming you've got some really big spending planned.
DBS is offering a 25% bonus on points transfers to Qantas Frequent Flyer till 31 Oct 2019. But given how abject Qantas Frequent Flyer is, you'll probably want to pass.
New-to-bank customers who spend $7.5K in the first 3 months of approval can get up to 30,000 miles. Plus, get $300 NTUC/Taka/Grab vouchers if you sign up via SingSaver.
Some AMEX cardholders who transferred Membership Rewards points to Hilton last year are still waiting for their bonus points to credit. My case got resolved...in a very strange manner.