my idea of changing LD would be to make it a aoe invul that your allies can also benefit from. So now drk can save not only themselves but the other tank/group members during a big tank buster or shared buster.
Drk pops LD, a big 10yalm wide aoe appears below them, now the drk and any ally standing in the circle gains the benefit of walking dead where they cant be reduced to 0hp. At the end of the timer (10's) every ally including the drk recover hp equal to 50% of their max hp.