The biggest thing you need to realize is that the Revenant player is a very story based option and is not really mechanically balanced. The combination of Regen 1 and the fact it is not automatically disabled when you are knocked unconscious means that you are almost impossible to put down as if you do not kill them instantly, they will regain 1 hp at the start of their turn, waking them up. Revenants really are relentless.
Furthermore, they know where your target of vengeance is supernaturally.
Finally, on success the hero dies. The Revenant is by definition a tragic hero, as at the end of his quest he dies forever. This is the tradeoff for being granted all of these powerful gifts rather than being resurrected in a normal manner.
In Short: Know you are giving the player a very powerful ability to be literally unkillable in the sense that even if killed, they will come back. And the player needs to know this character now has an expiration date.