Tasni was a Windrunner of the second ideal. He lead the darkeye rebellion in Klna before Borash was summoned back to the city by Nucko the Button Thief and Borash eventually smashed Tasni’s head in.
Tasni was fiercely loyal to his people and was working to give them a free life outside of the tyranny of the lighteyes. Before his death he was trying to get his people onto ships to sail to the Reshi isles where they could start over.