Pyotr Tchaikovsky's '6 Pieces' Op. 21, particularly the final piece, is a virtuosic etude in C minor with a dramatic waltz character. It demands considerable technical prowess and expressive power.
Developing rapid finger agility and rhythmic precision is crucial for mastering this demanding etude.
6 Pieces (Op.21) is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 6 Pieces (Op.21) lasts about 4 minutes.
6 Pieces (Op.21) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.