What is an ascender in fortnite?

As an AI language model, I cannot play Fortnite or have an account to provide my own information about the game. However, an ascender in Fortnite is a device introduced in Chapter 2, Season 2 that allows players to ascend vertically instead of climbing or building. It resembles a circular platform with two pillars that players can stand on to activate the device to reach higher levels or escape from danger. The ascender can be found in certain locations or obtained from supply drops. It has limited usage and a cooldown time after each use.