I'd rather have it be a neutral-cost Darkness creature with a zero/neutral-cost self-sacrificial ability, since its ability is basically a weaker version of reverse time that is currently cheaper than the next best vehicle's (eternity's) cost and ability, easier to fractal than the next best vehicle, and deals damage too.
It seems like that the ability is so OP that you're over-balancing the cost. With the cost as it is, the opponent can only counter it if it both has enough darkness quanta and wants to sacrifice playing his original cards to shift his strategy into playing Saboteurs.