One of the new feature of krita in 1.6, is the addition of an option to the duplicate tool to correct the perspective. This is useful, for instance, to hide an obstruction on a wall. Or if you want a perfectly good looking obelisk like in the following video (size: 3.0 MB, length: 1:01):
In the video, the bottom of the obelisk has been damaged, I want to fix that, so first I need to create a perspective grid fitting the plan of the front of the obelisk and I create a selection to avoid duplicating outside of the front of the obelisk. Then I can select the duplicate tool, and activate the perspective transformation. And during the remaining of the video, I duplicate an undamaged zone of the obelisk, on the bottom.