The Paul Nicholls-trained 11-year-old chalked up four successive World Hurdles from 2009 to 2012 as he swept to 18 consecutive victories over the smaller obstacles.
However, he was forced to miss last year’s race through injury and only returned to action in January, when he was third behind Knockara Beau in the Cleeve Hurdle on this course.
He showed the fire was still there and is expected to come on for the run in the hands of Sam Twiston-Davies, who rode him for the first time in that contest.
Ruby Walsh, who guided Big Buck’s to many of his victories, partners Willie Mullins’ undefeated mare Annie Power.
Mullins has also left in Quevega, who runs in the OLBG Mares’ Hurdle on the opening day, and the trainer said: “It’s just a precaution in case anything untoward happens this afternoon.”
Gordon Elliott’s Mala Beach and Rule The World, from the Mouse Morris stable, were the other Irish horses declared at the 48-hour stage.
As well as Big Buck’s, Nicholls has Celestial Halo, Salubrious and Zarkandar.
Cleeve runner-up At Fishers Cross, last year’s Albert Bartlett Novices’ Hurdle victor, and More Of That both carry the JP McManus colours.
Completing the line-up are last year’s Coral Cup scorer Medinas and Reve De Sivola, who was fourth in this race 12 months ago.
The horses withdrawn were Boston Bob, Thousand Stars, Trustan Times and Mickie.