yes, It could be done using the monotorrent library.
you could take the hash value from the magnet link and use it to create a torrent manager that will create a torrent file before downloading.
if this were the magnet link:
magnet:?xt=urn:btih:18981bc9759950b4715ad46adcaf514e6a773cfe
hash=18981bc9759950b4715ad46adcaf514e6a773cfe;
manager = new TorrentManager(InfoHash.FromHex(hash), downloadsPath, torrentDefaults, downloadsPathForTorrent);
this should download a torrent file to 'downloadsPathForTorrent', and you can stop the download as soon as it begins.
hope this helped.
for more information on how to implement this checkout the monotorrent documentation: