Third movement of the Rachmaninov 2nd concerto.
Many chords, in both hands, particularly in the coda, require every finger.
In the first movement, wrapping up the development, there's a handful of bruiser chords climaxing with the Maestoso section. If you aren't sweating at the end of those two pages, well, you don't have a pulse.
And of course Rach 3. Please. The longer cadenza is a monster chord-fest.