The skill is worthless to pick because of a certain Talent. It should have a bonus effect of some sort that discourages enemies from attacking you during it. So here's an idea:
"While under an Invocation status (or only Mercalan Invocations), you will receive -25% damage taken and there is a chance the enemy will be smitten by Divine Lightning (The one from Pray) upon attacking you."
"While under an Invocation status (or only Mercalan Invocations), you will receive -25% damage taken and there is a chance the enemy will be smitten by Divine Lightning (The one from Pray) upon attacking you."