My only concern is that, if played when you only have a few recruits so the reduction is ineffective, this is a very accessible and inexpensive way to pull a Rare into your hand to trigger the Legend keyword. The recruits reduction is only effective if one assumes that the player is summoning a card with the intent to actually play it as Undead cards are almost all thirsty for recruits. A way to get around abusing it for Legend decks use could be to require another Undead on hand. A player with no Undead in deck could still use this card to pull arbitrary Rares then, but it would take more setup.
I wonder if it shouldn't base the rarity on the card last played or discarded by the opponent rather than just a resource penalty. Given the name, such functionality would make sense.