Daphne and the others did not actually need to go to all that trouble over the potion.
After all, they all knew that the Horcrux inside was a fake, an impostor Regulus had put there.
But Sirius hoped to retrieve it and keep it among his brother's belongings, as a memento of the brother he had misunderstood for so many years, but who had ultimately done something braver than he had.
Daphne did not really care either way, but the former Gryffindors all thought it was very necessary. So she did not spoil their enthusiasm.
As far as she was concerned, retrieving a fake Horcrux should not have been difficult.
Yet reality fell considerably short of their expectations.
First, that Inferius Runespoor had given Daphne a fright. Had she come alone, dealing with that enormous creature might genuinely not have been easy.
Fiendfyre could certainly burn the thing to death, but once it entered the water, the Fiendfyre would instantly spread over the entire lake. Even with Daphne's current magical power, she could not sustain that level of magical expenditure.
Death from exhaustion caused by excessive magical expenditure was the most common way Fiendfyre killed. Yes, more people actually died from messing around with Fiendfyre without understanding it than were burned to death by it.
If the Inferius Runespoor, which Daphne had not known about beforehand, could be considered an unexpected accident, the poison before her now was rather beyond her expectations.
When she had watched the film two lifetimes ago, she had wondered why Dumbledore had to drink all of it. Could he not just pour it away?
Now it seemed that, indeed, pouring it away was not an option.
Not only could they not pour it away, but the other methods they tried did not work either.
First,