GVC, which also owned the Sportingbet and Bwin brands, would own 53.5% of the combined business and has until early January to make a firm offer.
Addleshaws is representing existing client GVC on the deal, led by corporate partner Nick Pearey, while Ashurst is advising Ladbrokes on another significant transaction, led by corporate partners Simon Beddow, Tom Mercer and James Fletcher. Competition partner Ross Mackenzie and tax partner Alex Cox are also advising.
Jones Day is advising Houlihan Lokey as financial adviser to GVC, with team led by Leon Ferera.
Addleshaws previously acted for GVC in its £1.1bn contested takeover of gambling company Bwin, which was completed in 2016, as well as its £485m takeover of Sportingbet in 2013.It also advised GVC on its transfer to a premium listing last year.
Ashurst, meanwhile, previously advised Gala Coral on its £2.3bn merger with Ladbrokes in 2015.
Gaming and betting has been a lucrative sector for law firms in recent years after a spate of consolidation, including a £5bn tie-up between Paddy Power and Betfair in 2015. Then last year, William Hill rejected a £3.6bn takeover bid from Rank Group and 888 Holdings, after 888 had failed in its bid to take over Bwin in mid-2015 for £898m.