This is Link vs. Twinmold, a boss from The legend of Zelda Majora's Mask.
As always I used as reference the game more than the official artwork because there are many different things in the characters.
Link is fighting with the gilded sword, the mirror shield and the Giant's Mask.
this is the second time I start with this one, because I did not like the first attempt.
So I hope you like this inauguration of LINK VS. MAJORA'S MASK BOSSES!