My favourite remains the Gratton offersheet.
Philly frontloaded it with a 9 million dollar signing bonus because Tampa Bay had cash problems. Phil Esposito knew he probably couldn't match, tried to claim the offer sheet was invalid because they couldn't read the fax, and traded Gratton's rights to Chicago for Carney, Moreau, and Dubinsky without telling Chicago that Gratton had signed the offer sheet.
The league upheld the offer sheet, invalidated the trade, and Tampa got 4 1st round picks, which they then traded back to Philly for Renberg and Dykhuis
Gratton had a decent season in Philly but got off to a slow start the next season and was promptly traded back to Tampa Bay... for Renberg.
https://www.hockeybuzz.com/blog/Bill...egins/45/45933