Limited time offers with unnecessary urgency.
"Whenever a legendary drops, it immediately offers you the chance to fully level them for a cost... which expires at the end of a day."
"Special offers for new or specific characters are a limited time offer and then either become unavailable for a time or available randomly through other non-limited, randomly generated offers."
"Yes, unlock a tier 8 reward or premium vehicle in a week that requires at least 60 hours of gameplay if you are good. And these events are pretty frequent."
"Limited events, both Holiday events and non-holiday events. The events come back every year."