I believe the unupped Luciferin should get -1
cost.
I have long experimented with newbie-level Luciferin/Hope decks but find, surprisingly, that 2
is a big hindrance. As it stands, the card is hardly too powerful, so I believe this will make the card more playable.
I am not currently concerned how the upped would be buffed if this happened, but I expect it would either be the same cost reduction (at the additional price of interfering with the mulligan), or heal more HP.