As turbine inlet temperatures are pushed ever higher in an attempt to improve efficiency and power, it has become critical to cool component surfaces. One surface that is particularly difficult to treat because of the complex flow field that surrounds it is the nozzle guide vane endwall. Past studies have indicated that leakage bypass flow emerging from the combustor-turbine junction may be effectively harnessed for cooling purposes. When combined with endwall film-coolant injection, component service life may be significantly extended. This paper presents results from a computational study investigating a three-dimensional slot geometry at the combustor-turbine interface. The downstream edge of the slot was scalloped using a simple periodic function intended to enhance thermal benefit to the endwall by manipulating coolant distribution. Effects of varying the slot geometry amplitude and phase were investigated along with the slot nominal width and upstream distance from the vane. Initial results indicate dramatic effects can be realized depending upon the scalloping used.