Named by The Games Detective, this is a particular style of event in survivors-likes where the movement of the player is usually limited and a large amount of enemies spawn in a surrounding posture. True, many late games you are constantly surrounded, but this particular ‘ring of moving enemies’ tactic has been very popular in games inspired by Vampire Survivors – many of which directly mirror the circular formation and triggering events. In Death Must Die there is often a rectangular space with black flame style effects around it, which traps you while enemies spawn around. It’s a similar mechanic. It’s not unique to this genre – it’s common in many popular games – Destiny for example! Enemy Trap is named due to common triggers of certain find/pick up based events (like a ‘trap’ from a chest or a cursed shrine) but they are also commonly triggered by the game timer, boss arrival, or other conditions. We just call them enemy traps to have a unique name for the moment.