Vertigo Mid Boost Flash from Iron (Middle)
NOTE: This is an underhand ("right click") jumpthrow whilst crouchwalking.
A nasty pop flash that leaves enemies holding from CT or Window no time to react. On the downside, it might not catch the ones holding deep angles in Elevators or behind the Mid Boost. Therefore, you or your mate should not swing too wide with it and only try to catch people holding said positions. This makes it the perfect choice for Wingman matches, too.
Alternatively (or additionally), use this flash that catches all positions in Middle and works as a pop flash for Elevator, but can be seen a mile ahead from Window.