Alerts, Events, Sorties + More
Alerts
Alerts are temporary, usually lasting between 30 and 70 minutes (doubled if the bonus award is a special item) and issued at intervals of 20 to 40 minutes. They spawn linked to a specific mission and are available to any given player until the time passes or until the player completes the alert. The timer restricts the time in which the alert can be started; the alert must be completed within one hour of expiring in order to grant the reward. There is almost always at least one alert available, and as many as 5 alerts can be available at once. If you do not have the node unlocked where an alert is taking place but you want to go, someone can take you that has the node. The term is called "Taxi-ing".
Some alert rewards are alternate Warframe helmets, weapon blueprints, credits, Orokin Catalysts, Orokin Reactors, etc.
Some alert rewards are alternate Warframe helmets, weapon blueprints, credits, Orokin Catalysts, Orokin Reactors, etc.
Events
Events are large scale alerts that usually last longer than 24 hours. Participating in these events will reward the player with rare or brand new equipment, blueprints or Mods.
Sorties
Sorties are a set of three special missions that are assigned to players on a daily basis. Each Sortie consists of three missions of escalating difficulty that must be completed in sequence; preceding missions must be completed before proceeding to the next one. The individual missions in a Sortie each have their own unique hazards and conditions that make the mission more difficult, from loadout limitations to enemies with enhanced offensive or defensive abilities. You must have a level 30 Warframe and have also completed The War Within quest. Each mission has its own special condition and a reward that you can only receive through sorties.
Invasions
Invasion is a mission type that allows players to team up together with the Corpus or the Grineer to work against the opposing factions, as a faction invades a specific mission sector. It was first introduced in The Gradivus Dilemma and officially added to the game in Update 11.3. The Infested also are able to invade, although players cannot side with them. With Invasions, you have to complete the mission three times in order to receive your reward.