My favourite hologram trick is to have a sword and send out the hologram with the sword. People sometimes get wise to the hologram when it's got a gun, but when they see the giant glowing sword heading at them, they panic. I follow in behind with my DMR and at worst I get several free shots on them as they try to take down the sword-o-gram, but a lot of the time I actually kill them while they're still fighting it off.