Partners from Fraser Milner Casgrain, Salans, and SNR Denton voted Wednesday to approve a three-way merger that will create Dentons, a 2,500-lawyer global giant boasting one of the world’s largest energy practices.

SNR Denton issued a press release announcing the decision by the partnerships of all three firms to approve the union, which will go live in the first quarter of 2013.

The Am Law Daily spoke earlier this month with SNR Denton global CEO Elliott Portnoy and global chairman Joseph Andrew about the merits of the merger, with leaders from FMC and Salans also offering their take on the proposed tie-up.

News of the megamerger was soon shunted aside by Norton Rose and Fulbright & Jaworski, which seized headlines by announcing their own union to create a 3,800-lawyer global legal giant called Norton Rose Fulbright that will also have a formidable energy practice. Fulbright, which as we’ve previously noted was once approached by SNR Denton about a potential combination, won accolades for its deal while others were more skeptical of the merger creating Dentons, according to a survey by British publication Legal Week. (Both mergers will use the increasingly popular Swiss verein structure, in which each legacy firm maintains their own profit pools.)

Nonetheless, leaders of the new Dentons have been busy in recent weeks touting their brand, with Andrew telling British legal newspaper The Lawyer that the firm will be among the “most multicultural” in the world.

While Dentons’s “polycentric” business model will result in it having no global headquarters, two of its predecessor firms, SNR Denton and Salans, have some overlap in their offices worldwide. The process of streamlining those operations has already begun, with Legal Week reporting earlier this month that SNR Denton had sublet a floor of its London office to Quinn Emanuel Urquhart & Sullivan. Andrews also told sibling publication Texas Lawyer that the combined firm intends to close one of the few holes remaining on its energy map by opening an office in Houston to gain a foothold in Texas.

Last week SNR Denton grabbed a role on its first major energy M&A deal since announcing its upcoming merger, advising French energy giant Total on the $2.5 billion sale of its 20 percent in an offshore Nigerian oil field to China’s Sinopec. Just prior to its own merger news, the firm also quietly represented longtime client Nokia on the reported $250 million sale in late October of its Vertu luxury phone unit to Swedish private equity firm EQT, according to Legal Week.