I would design the death cards to require finite life for full effect. Thematically, it is the fear of death that is exploited by the dark wizard, and bravery and priest cleansing that is the undoing. I can imagine the epic battle of good versus light evil, with the tide of battle turning at the fall of the Deathlock (for example).
I think this would make Finite Life much more interesting.
Death
Incantation
Cost: X+X
Full Action
Range: 0-0
Target: Creature
Level: Dark 3
Target creature loses X life. Then, if it is not destroyed, it gains X life.
Unstable Affliction
Enchantment
Cost: (2)(X)
Quick Cast
Range: 0-2
Target: Living Creature
Level: Dark 3
Dark Mage Only.
X is the level of target creature.
This creature gains Finite Life.
During the upkeep phase this creature loses 1 life.
When Unstable Affliction is destroyed by an opponent place X Rot tokens on this creature.
Fear
Incantation
Cost: X
Quick Cast
Range: 0-2
Target: Non-Mage Living Creature
Level: 1 Dark
X is the level of the target creature. If the creature has finite life, immediately activate and control that creature but take only move actions.
Searing Pain
Incantation
Cost: 5
Full Action
Range: 0-1
Target: Creature
Level: 1 Dark
If the creature has finite life, place a stun marker on it.