Keep in mind that we are using this naxx 25 relic to reduce 9 Dragons Gold Rejuv mana cost. The actual stats on it say reduced mana cost by 106. Now take into account mana reducing talents it makes it actually -91 in caster form and in tree form only -70 mana per cast. To great, but we make use of Rejuv so much we think it matters. If not go for the Lifeblood Trinket clearly.