Honestly I do like the one-turn delay for DeathMark. That said, I propose to make it a bit stronger, say a 20% chance for it to proc on the second turn. Think of it as a penalty for not bringing a cleanser on your team. Maybe even have the DeathMark proc chance increase at the same rate as the self-cleanse percentage - 20% to either die or cleanse on turn 2, 30% chance to either die or cleanse on turn 3, and so on. It would definitely bring back some nail-biting tension!
Now that we are being introduced to class-specific traits (I’m sure more classes will get this treatment in the future) I feel that some classes should have a particular weakness to a particular Status Effect or elemental-based magic. For example, Undead takes double-damage vs Burn status or fire-based (red) spell dmg. Divine has a higher rate of having DeathMark proc on them and double dmg from dark (purple) spells. Fire-based troops will have a reduced chance to cleanse Freeze, plus it will cause dmg each turn like a cold burn.
This would require a lot of tweaking and determining what spells can cause elemental damage but I think it would be awesome!