Warden has no execute. At least not for PVP. I guess technically, someone might say that bear ultimate is an execute. But it is just about impossible to control or use in a timely way in PVP.
I try to time ice comet to hit with the second, nine second iteration of deep fissure. That’s as close as I can get to execute using a staff on my warden, which is why in battlegrounds I get a very high number of assists, and not many kills.