Today quest is Death Quest, win 5 match with death element.
from the match I won, found out that Haunted Spirit is the first card I picked.
The healing ability is really good as tanker.
Or you can choose Bone Golem.
Then look for Sneak ability, Snipe ability, and/or Opportunity ability cards.
Ended with Undead Priest.
After completed the quest, I received this. Still figuring out how to use it.
Please comment if you know, thanks.