About

When the boss has a second phase is a catchphrase summing up the look of surprise and dread videogame players may experience when facing a difficult enemy which, after being defeated once, happens to rise back up again and starts attacking them in what is called a second phase combat. Images and videos were made on that subject alone as a result.

Origin

While boss battles divided into differents parts, or phases, has existed since the dawn of videogames, especially RPGs, this very niche concept in having a specific difficult boss battle entering a new combat phase after being defeated once mainly became a staple joke within the Dark Souls franchise and its community.
As a matter of fact, one of the earliest mentions coupling this specific situation with a reaction image comes from a Darks Souls related sub-Reddit called r/shittydarksouls^[1], from August 6th 2018, also referencing Disney's The Incredibles.
That same year, on November 19th, X user ProTayToe (now suspended) made a similar joke, this time referencing Flapjack (screenshot posted to iFunny in December 2018^[2] shown below):

Spread

On June 26th 2019, YouTube user Erynith uploaded a video titled When the boss goes straight into second phase (shown below), depicting a mascot approaching children before headbanging hard to the tune of Dark Souls' boss music. It accumulated to over 16 million views in the next 5 years.

Elden Ring

As shown on the Google Trends graph down below, the phrase started really taking off following the release of Elden Ring in Ferbuary 2022, in which it became quickly associated with Malenia, a popular boss character widely known for its second-phase battle.

Popularity as a catchphrase

External References

^[1] Reddit – When the boss reaches second phase and immediately starts chasing you

^[2] iFunny – When the final boss has a second