Sumner is the protagonist in Gauntlet: Legends and Gauntlet: Dark Legacy, aside from the heroes. He has the ability to unlock new Realms for heroes and give hints as well. He is mostly seen in action in the introduction, ending, and "Game Over" video clips throughout the game.
His appearance in-game is in the center of his tower, infinitively reading a book which is assumed to be a spell scripture. He unlocks new worlds when the player finds enough Obelisks in Legends, or Crystals in Dark Legacy. He is a font of wisdom and has many important hints, including Runestone locations, and tips for defeating bosses. It was he who scattered Scrolls around the Realms. He also serves as the shopkeeper from which heroes may spend their hard-earned Treasure.
In the Fortified Towers level of the Battlefield, there is a secret Coin Room which will unlock Sumner as a playable character. All of his stats will be at 999, and his maximum health with be at 9999. He also has all the crystals, shards, and runestones. He also has the same skills as the normal Wizard.
Sumner is the older brother of Garm, both being powerful Wizards in their own right. After seeing the havoc that Garm had caused with the unsealing of Skorne, Sumner called forth the heroes to save the Realms.
In Dark Legacy, he also makes an in-game appearance after a boss is defeated. He appears as a floating transparent "ghost" and summarizes the player's progress for that Realm.
- The symbol on Sumner's robe is the same as Garm's, except it is in a square, where as Garm's is in a circle.
- Sumner's name is a shortened version of "Summoner", referencing his summoning of the heroes to his tower following Skorne's unsealing.
- In Gauntlet: Dark Legacy, using the name code "SUM224", lets you play as him from the start without having to complete the coin room. However, unlike Gauntlet: Legends, he is instead replaced by a reskinned yellow Wizard.
- Sumner was also utilized in the expanded version of the game Gauntlet: Dark Legacy. it is also noted that regardless of color choices chosen for the character Sumner he will always retain his yellow robe unlike all the other characters within the game.
- Sumner is likely a homage to the wizard from the games prior to Gauntlet: Legends, Merlin, as both are elderly wizards that predominantly wear yellow-colored clothing.
- Sumner was created during a contest held in 1991.
- Doug Lawrence, the voice of Sumner, also did voice work for various Nickelodeon cartoons. He is most known for being the voice of Plankton from the SpongeBob SquarePants television series.
- Sumner is similar to Zordon from Power Rangers in several ways, such as the two being mentors to their team and also sound similar to one another. In addition, both are powerful wizards who spend most of their time in the bases of operations, and summoned heroes to help fight their respective enemies.