Oh, man, just remembered another one!
A couple of years ago i was playing the original Horus Heresy board game with some pals, with myself in control of the Imperial forces. The battle was very heated, massive casualties on both sides.
It finally came down to the Emperor teleporting up to Horus's Battle Barge with whatever units were with him at the time.
Just before they went up, I noticed a unit a few squares away from the Emperor which would really help... the Sky Fortress!
So yes, the Sky Fortress drifted on over and was caught in the teleporter beam! Horus got the fright of his life when he was flexing his talons in eager anticipation of a final showdown with his father, when all of a sudden he was looking down the barrel of a bombardment cannon.
Horus was atomized, and the Emperor survived!
A rules technicality seemed to have saved the Imperium from 10,000 years of decay... until the Horus Heresy novels were published.
Therein was a description of Horus's Battle Barge, the main hall of which was described as being able to fit a smaller Cruiser. As the Sky Fortress was smaller than a cruiser, my tactic was sound!
The Emperor really missed a trick with that one!