There is most certainly a plot to be played with the gifts of rebirth, yeah – but that’s not to say they’ll be particularly rigidly tied to the plot either. A lot of the utilization of gifts of rebirth will be in certain moments of despair and will focus more on characterization and plot purposes then just “time to use my special power!” syndrome that is often seen in scenarios like this. But I will state that the idea behind it is to give powerful albeit dynamics abilities that are untapped to the party at a given time.

That probably sounds like a mess, though.

As for suggestions, the only tertiary powers I came up with during the "alpha" stage of the RP was:
[list][*]The ability to become imbued with the full power of divine holy energies; so Holy Conduit.
[*]The ability to become invulnerable for a limited window, impervious to all damage; sort of like stoneskin.
[*]The ability to become lightning fast for a limited window, easily traversing around an enemy.
[*]The ability to become invisible for a limited window, etc.[/list]