It's worth noting that in the Curtained World, unless in specific cases, mages typically transform natural or non-elemental mana into magic, which then manifests as various effects or elements. They don't directly utilize elemental mana, unlike Daniel who actualized spells directly from the card using elemental mana.
When Greed mentioned Sacred Grounds, Daniel had no knowledge of what they were. These were exclusive locations where elemental mana could be found, and there were fewer than 10 known sites worldwide, with 7 of them already occupied by various groups or organizations. The Hightower, in particular, controlled 3 of these locations.