The 10-year-old is one of 40 entries received for the extended four-mile contest, which is worth more than £50,000 to the winner.
After finishing second on his final start last season in the Midlands National at Uttoxeter, Mysteree was pulled up on his return to action in the Welsh Grand National at Chepstow in January.
Scudamore said: "Obviously it was a great day last year when he won the Eider. The plan first time out was the Welsh National but things went wrong that day.
"He has come back in great form and he hardly had a race that day. Obviously it was frustrating that things didn't go right on the day at Chepstow but he came back in one piece and that was the main thing. He seems as enthusiastic as ever.
"He has got an entry in the Grand National Trial at Haydock. We will sit down and have a chat with the owners and see what Plan A is in the coming weeks and see what route they want to go down.
"We know stamina is his forte and four miles around Newcastle brings out the best in him and we had a great day there last year."
Paul Nicholls, who has yet to win the Eider, has entered dual Scottish National winner Vicente and Silsol, while Milansbar, from the yard of Neil King, could bid to back up his last-time-out success in the Classic Chase at Warwick.
Venetia Williams, who won the race in 2007 with Nil Desperandum, could also be double-handed with Houblon Des Obeaux and 2014 Welsh Grand National hero Emperor's Choice.
Last year's runner-up Knockanrawley is one of two entries for Kim Bailey alongside Harry Topper.
Irish interest in the race comes from the Patrick Griffin-trained pair of 2012 Eider winner Portrait King and Maggio, the Eric McNamara-trained Dare To Endeavour and Thebarrowman, who is the representative of Adrian Keatley.
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