The problem is that the Ruin Thiefs tribe isnt vampires
1 Naya Charm
The theory behind it was that cards that used it were slightly weaker than other cards of similar mana values, but you could bring them back to your hand by milling a certain number of cards (which varies depending on the Dredge card) any time you would normally draw, and they would help you find other dredge cards in the process
However, Wizards underestimated the Critical Existence Failure aspect of Magic, leading to competitive players aggressively paying the 2 life for powerful effects they shouldn't get on their deck colors, making Phyrexian mana responsible for some of the biggest color bleeds in the modern color pie
Are you running them as synergy pieces, or generic card draw engines
Its indestructible, so it should get into combat easily, and just a small Giant Growth can make you steal that many cards