as a stam DK I just find the Templar in question and spam wrecking blow....because I played a magDK till a couple weeks ago. Im still learning if I should spam wrecking blow or just spam it A LOT till I get into execute range and then skip right over executioner and go for one more wrecking blow.
As a magDK it was all about sustain till you could stack/time a major sorc buff/proxy/ leap or shooting star for a quick burst then whip them down. if you could wait till the CC immunity wore off and get a quick talons on them you could add a little more dps if it wasn't enough burst to take them down. If running fossilize doing that combo it would be: get the proxy up, get major sorcery, cast meteor then fossilize. They would sit there fossilized unable to do anything and take a full meteor to the face, rush in for the proxy then whip till it was a fluffy consistency.
Sad part of playing a magDK solo, for me, was my dots were pretty much useless. So unless I could get a burst chain combo it was basically a fight of sustains when it came to Templars.
if its a stam temp, I did the same. One thing I would try to remember was to time blocks to keep from being CC'd from jabs.
EDIT: I just re-read the title and realize I gave away all my DK brethren's secrets.....nevermind I said anything