Prayer - m. Water. It implies that one prayed, drank some kind of holy water, and felt refreshed, etc. The question about lightning is debatable (50/50). Clouds without water (vapor) do not exist, just as there is no thunder without rain and no thunder without clouds. We attributed it to air magic for the balance of magic schools. And besides, there is a lightning bolt (initial level of magic, either level 1 or 2) that can belong to any school. This is where the fantasizers went wild...

Added 3 minutes later
If spatial gates are made with earth magic, then why is air magic needed? Only to increase the speed of units?