So the Harrow Mat has the following line
When this mat is used to perform a harrowing (magical or not) over a grave or other burial site, the spirit of the interned body influences the harrowing; for each card drawn related to the past, the harrower can draw from the deck twice and choose which card to place.
So say for example, I'm doing Harrow or Greater Harrow, and I'm suppose to draw nine cards. Do I have the ability to draw twice each card from the deck? Or is it only specific cards or something?