Loki was sent to the creature's dimension and was tortured by having venom dropped in his eye, possibly until the end of time. Loki was briefly freed from the Midgard Serpent by Enchantress, but was then sent back after he failed her.
After retrieving the Codgel, Doctor Doom with a little modification uses the weapon to release the Midgard Serpent with hopes of using it to conquer the entire globe. The creature was so powerful that it would grow until it could consume Earth. After a battle with the Avengers, he and the creature are banished to the Realm Below using the extra-dimensional portal used by Ulik.
This version of the Midgard Serpent had small arms and appeared to be more amphibian-like than reptilian.
Trivia
In Norse Mythology, the Midgard Serpent is one of Loki's monstrous children along with the giant wolf Fenrir and beautiful/ugly hybrid humanoid Hel.
