Troyki is a form of Khowar/Chitrali poetry initiated by the khowar poet rachitrali. Unlike sher, a Troyki consists of three "hemistichs" (misras). The first two are complete in themselves but the addition of the third misra gives a new dimension.
Example
A beautiful example of Rachitrali's Troyki:
اللہ مہ خودای تہ نام رحمان دی رحیم دی تو غفار دی، غفورالرحیم دی کرم کوس اسپہ سورا تو رب کریم دیReferences
Troyki Wikipedia(Text) CC BY-SA