A turbine assembly has a casing, a turbine ring and a blade. The blade has a root portion having an axially extending first shape, an airfoil attaching to the root portion and having a trailing edge and a radially outward tip. The tip has a first portion disposed in parallel to the axis of rotation for minimizing escape of air between the tip and the casing and a second portion extending aft from the first portion at an inward angle. The ring has a cut-out having a second shape mating with the first shape.