Location from Invincible by Robert Kirkman
An alternate dimension where time moves far faster — the alien warlords who keep invading Earth have had generations to plan between each attempt.
The Flaxan Dimension's time differential is its defining feature: years pass there while days pass on Earth. This means the Flaxans have generations to study Earth's defenses, mourn their dead, develop counter-strategies, and build new invasion forces between each attack. Omni-Man devastated the dimension when he pursued the Flaxans through their portal, living as a conqueror there for what felt like years to him. Robot later spent decades there perfecting his governance skills.
An alien world with yellow-tinted atmosphere and architecture that evolves visibly between invasions — each time the portal opens, the Flaxan civilization has advanced decades or centuries. Technology, armor, and weapons become progressively more sophisticated with each incursion.
Also known as: Flaxan Dimension, The Flaxan World