For a dominant buck during the rut use a series of 'tending' grunts (the vocalizations that a buck makes when courting/chasing an estrous doe). Can't explain the sound nor method of doing this type of call/vocalization on here, but I am sure there are numerous videos or recordings out there that you can learn the technique off of.

Using the tending grunt sequences sold me on it last year. I taught it to a friend and he and his son spotted a buck trotting away from them about 300 to 400 yrds away. He used that calling series and had the buck RUN at them and get within 35 yrds before his son bagged the nice 135" 8 pointer with one shot.