This resource can be used instead of Gold to revive your troops. Your Temple produces Sacred Potions constantly until it's at capacity. Your maximum capacity of Sacred Potions is also determined by your Temple. The cap can only be increased by obtaining the Nectarius avatar, while the speed at which Sacred Potions are produced can also be increased by researching the relevant technologies. You can also get Sacred Potions in Clan chests, packages, or as rewards for reaching new battle pass levels in the Triumphal Challenge.
Sacred Potions benefit from the Temple's troop revival cost reduction in the same way as Gold.