The Sasori puppet's puppeteer can shoot fire from the pipes in its hands, making them like flame-throwers. The flames are fierce enough to melt rocks and incinerate a metal kunai that was thrown at it near instantly. The ammunition is sealed in the first scroll on its back. By utilising his water cannons onto areas that have been previously heated by the flamethrowers, Sasori can cause even rocks to crack via thermal shock, enough to send debris flying with great impact.
During Kankurō's use of the puppet, the ammunition scroll is nowhere to be seen, implying that the flame-throwers may be used without it.