The JP McManus-owned nine-year-old is lucky to be alive after collapsing in the closing stages of the JT McNamara National Hunt Chase at last year's Cheltenham Festival.
With the final race on the card that day delayed by 10 minutes as he was being treated, Edwulf was eventually moved off the course before being loaded into the horse ambulance.
He was transferred to an equine hospital near Tewkesbury where he was nursed back to health before going back to Ireland two weeks later and eventually returning to training.
"Edwulf is very good, thankfully," O'Brien told Press Association Sport.
"It was extraordinary what the vets did to help him at Cheltenham and the lads in the yard, they all deserve a huge amount of credit.
"There was never a plan. All the time we were just going to see how he was all along, but there was no plan to do anything with him.
"He looked very well and seemed in very good form, but even when he came back into training, it wasn't a certainty that he was going to even run again.
"It was literally just step by step all the way and he kept ticking all the boxes.
"All his work was good, he was in great form so we had no reason not to run him."
While he may have been pulled up in the Leopardstown Christmas Chase on his first run back, he showed enough to connections that he was worth persevering with in top company and they were rewarded in the best possible style.
O'Brien said: "We weren't thinking of winning a Grade One, we just wanted to get him back racing as he was a lightly-raced horse.
"It would have been a shame to have him stood in a field for the rest of his life when he could have been doing what he loves to do.
"It was a wonderful day, but it really is a credit to everyone who has worked with him along the way.
"Derek (O'Connor) gave him a wonderful ride. He believed in the horse and has a great association with him.
"I'll have to talk to JP and Frank (Berry, racing manager) and see what they say, but I'd love Derek to ride him if he goes to the Gold Cup, anyhow."
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