Victory? - Heart still standing

[Mark]

New to the game here. I finally killed the boss on the last act, and a corrupt heart appeared. The came calculated some damage based on my progress, but "it wasn't enough".
First time it happened I thought "OK, next time I'll do better."

It's been 5 times I beat the final boss, and even though I dealt over 1000 damage to the heart, it's still not enough, my guy collapses and the "VICTORY?" message appears.

What am I doing wrong? Last time I had a murderous hand, killed a boss on turn 1 and even killed the Transient before it faded.

Thanks

[ponjdug]

You have to reach the heart as the ironclad, silent, and defect. After that you’ll notice 3 keys appear in game (red, green, and blue). I don’t want to spoil too much so I’ll leave it there for you to figure out what you do with them.

[HAWAIIANpikachu]

That's what is supposed to happen normally.

[Geardo]

Keys?

I reached the heart as Defect and Ironclad, never saw them.

Defect said he attacked twice and won then that symbol appeared with 1 of the 3 lit, I presume it was for him.

Ironclad said he attacked once, died, gave me Victory? then the same symbol but with 2 of 3 lit.

Statistics page in game says I beat the game once with both.

The heart thing just seems weird.

[Rio]

you have to win with the silent once too, to start seeing key pieces.

[Nibbie]

Getting to the heart by beating the third boss and hitting it before fainting is a win. The damage you do to it is your score for the run. The "true ending" involving the keys is optional, and even if you die there, the run counts as a win (at least for ascension).