User blog comment:Roxashasnoheart/Who would win? Alduin or Mehrunes Dagon?/@comment-3076045-20120527140446

Alduin would defnitely win this fight. For reference, see the end of TES:IV. Akatosh's first-born can probably be assumed to have roughly the same powers as his earth-bound avatar, which defeated Mehrunes Dagon (albeit a Pyrrhic Victory). Nevertheless - I would have to go with Alduin.