Gray enjoyed a good first season in the Premier League last time out with the Clarets but a fall out over a new contract saw him move on to Watford for £18m last summer.
He now returns with his new side on Sunday and Ward says the Clarets' defenders will be well aware of what is coming their way and how to deal with it.
He told the Lancashire Telegraph: "We'll just get one of our lads to kick him early on.
"We know all about him and it'll be good to see him. We all know what he did for us. He's got pace, power, he can score goals, it's as simple as that."