Caretaker dao lets the user know what the target needs to get better. Lich was using this as a filler dao in his defense stat as he didn't know what to put in the defense stat. Though if he was taking care of dangerous things, this stat being in the defense would be a godsend.
Baptise dao is used to wipe out all foreign substances in the target and then use the material to strengthen the target. They will not only take reduced damage from the dao that was used but they will also deal more damage with using that dao.
Link Life dao allows the user to choose a target and their life becomes linked up with the user. All damage and healing is split between the target and user. Trump Card dao is a dao that is a life saving item. With it in the defense stat, the user can use a trump card per Tier that last a second per rank.