Finale

"I have not...come this far...to die now!"

- Nick

The Finale of a campaign is something akin to a "boss fight" in other games. It is similar to a Crescendo Event, though on a much grander scale.

Waves
The finale has five waves, and each wave is the same for every campaign. The Witch is the only Special Infected that is never spawned in a wave. Even though the Survivors are given a time-frame for the arrival of the rescue vehicle, it could take longer or shorter than this time depending on how long it takes the Survivors to make it through each wave.

First wave
The first wave does not begin until the Survivors have used the radio to call for help, or have started the fuel pump in the case of the Runway Finale. This wave consists of three to four groups of horde. Smokers, Boomers, and Hunters can appear during this wave. It begins roughly ten seconds after the countdown has been initiated, and is heralded by a loud cry from the Infected.

Second wave
The second wave begins once all of the Common Infected from the first wave are killed. Any Special Infected that are still alive after the first wave will continue to cause the Survivors grief. The second wave consists of an attack from a Tank. No Common Infected will appear during this wave unless an AI or Human controlled Boomer has vomited on you.

Third wave
The third wave is similar to the first, but there are more groups of Horde and the size of each group is larger. Special Infected also appear more frequently during this wave.

Fourth wave
The fourth wave is another attack from a Tank. This Tank usually attacks from a different direction than the first Tank attacked from and the same as the second wave, there is no horde, unless an AI or Human-Controlled Boomer has vomited on you. At The Plantation this wave consists of two tanks.

Fifth wave
The fifth wave begins after the second Tank has been killed. The rescue vehicle will arrive shortly and the Survivors must fight their way to it. This wave is the largest of the five and consists of several groups of hordes, and a Tank. The Infected will continuously respawn, with Tanks re-spawning every couple of minutes, until the Survivors escape in the rescue vehicle or die. Interestingly, Special Infected will not spawn for this wave, and any remaining specials will not be replaced on death.

Left 4 Dead 2's Finales
During The Parish's finale, you will be constantly moving. The Infected will be attacking from every direction possible. As you move forward, areas behind you will be made unavailable by various means. You will of course be heavily attacked by the Infected. Tanks have set points along the course to spawn at, instead of appearing at a set time.

Dark Carnival, Swamp Fever and Hard Rain's finale has been described to be like the first game's: defending a certain point from the Infected while waiting for rescue to come to you. Dark Carnival has unique music for each wave, while Swamp Fever has two Tanks appear at the same time during the fourth wave.

Dead Center's finale works in a way similar to Scavenge Mode, requiring the Survivors to find gas cans throughout the area and bring them to the rescue vehicle.

Trivia

 * Of all the Finales, only the Runway Finale, The Concert finale, Town Escape finale, The Bridge (Left 4 Dead 2) finale and The Truck Depot Finale provide an explanation for the appearance of the horde (all of these Finales involve loud noises or lights).
 * The Town Escape Finale in Hard Rain has an interesting twist; it is the same spot from the beginning of the campaign, and this is the first time the same rescue vehicle from the last campaign is the rescue vehicle for this campaign.