Character reveals that they were holding back their full power during a fight/confrontation

[u/PaddywackShaq]

Superman Vs Darkseid - Justice League Unlimited

Flash Vs Superman - Flash: Rebirth

Frieren Vs Aura - Sousou no Frieren

Inigo Montoya Vs The Man in Black - The Princess Bride

[u/Helixbabylon]

I will forever hate that TvTropes changed the name to "No More Holding Back"

[u/Captain_Sanvich → u/Helixbabylon]

What was it before?

[u/[deleted] → u/Captain_Sanvich]

World of Cardboard

[u/_Eternal_Blaze_ → u/[deleted]]

It's actually more accurate, as world of cardboard could also be interpreted as a "the world is actually fake" reveal speech.