Surt is from Muspelhiem and leads the Sons of Muspelheim army in the battle of Ragnarok. Surt is an antagonist in the Norse, of Course! stories as well as in Norse legend and mythology.
Features to include when drawing:
Shades of red skin color, looks like molten lava
Hair is optional, can be black, or like fire
Red or black eyes
Facial hair optional
About the same muscle tone as the Gods
Generally scary looking
Helmet and armor in a warrior style
Weapons can be axes, war hammers, swords, or the like. Just style them differently than the Gods.
Surt has the Fire Sword that he uses at the onslaught of Ragnarok
Don't depict him as "giant" literally, or gigantic, but roughly the same size as the Gods. Think larger than life, leader/king of a realm or kingdom. The mythological depiction is a metaphor for reputation, symbolism, and/or what he is known for.
Surt represents and personifies, and is the source of influence of jealousy and envy.