I've only found two Divine Skills to be useful:
Divine Death is a high damage spell on some enemies, useful some of the time.
- Level 1 Target must have spiritual resistance 10 or die. Inflicts 100+110 damage
Magic cost: 20 - Level 2 Target must have spiritual resistance 20 or die. Inflicts 100+120 damage
Magic cost: 21 - Level 3 Target must have spiritual resistance 30 or die. Inflicts 100+130 damage
Magic cost: 22 - Level 4 Target must have spiritual resistance 40 or die. Inflicts 100+140 damage
Magic cost: 23 - Level 5 Target must have spiritual resistance 50 or die. Inflicts 100+150 damage
Magic cost: 24
I believe that what this means is that if your enemy has under the spiritual resistance they need to resist, they die. If they have more then the spiritual resistance they need to resist, they take massive damage instead, but I'd have to load my character and check for sure.
Heaven's Blessing is an extremely useful self-buff that boosts all your stats and resistances by a lot for a long time. Max this and try to keep it active all the time.
- Level 1 All your primary statistics and your resistances gain a 20 % increase. It will last for 30 seconds.
- Level 2 All your primary statistics and your resistances gain a 25 % increase. It will last for 60 seconds.
Magic cost: 21 - Level 3 All your primary statistics and your resistances gain a 30 % increase. It will last for 90 seconds.
Magic cost: 22 - Level 4 All your primary statistics and your resistances gain a 35 % increase. It will last for 120 seconds.
Magic cost: 23 - Level 5 All your primary statistics and your resistances gain a 40 % increase. It will last for 150 seconds.
Magic cost: 24