How does the Restore mechanic works? is it like a battlecry? And the Locust Swarm card is just OP, It's a 2 damage AOE, reducing maximum health/attack at the same time for 3 mana. And for the record, there is no 3 mana AOE / 2 damage spell that don't have a drawback. Shaman's spell damage have overload, and Hunter's Powershot limits 3 enemy minions.
Best cards here imo are Locust Swarm and Touch of Light. Touch of Light is the Priest version of Shield Block and it's pretty much what Flash Heal should have been, and Locust Swarm has a really flavorful ability for its concept. They should probably cost more though, especially Swarm. Reducing all enemy minions health by 2 is pretty much the same as doing 2 damage across the board (i.e. Holy Nova, Consecration, Blizzard), except it bypasses the effects of minions like Acolyte of Pain and Imp Gang Boss.
Many of the existing Priest cards should not be in Priest. Priest either heals or is a DPS (so, basically, Aggro) class. Not a thief. There is a reason why "face melting" was a thing since the early days of WoW. Shadow Priest.
I took a little flavor from warlock and paladin when making a few of these cards. Regardless, some of the ideas and text in other classes could be what priest needs.
Warlock already has has twisting nether and doom, so I thought soul harvest may be good for priest because it solves the problem priest has with removal, and it gives a solution to aggro decks late game. Perhaps the name itself kind of sends the warlock vibe - but I think it would be better in priest.