Cyllenes use is reserved for cards such as Fire Crystal, Superior Energy Retrieval, Pal Pad, Vs Seeker, Rescue Strecther, Super Road, therefore generically recovery cards, but it can also regenerate Rare Candy by bringing 2 phase 2 in the same turn, so flip well
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On the other side of the coin, if this did improve Pox, that would be good for opposing decks like Delver, with cheap creatures, some burn spells, and Murktide Regent, possibly the best dragon in Magic, which can utilize that swollen graveyard
Then the Vampire was printed next, same cost, this time it adds flying and +1 toughness, but it just works once per turn so it's both better then Mentor (flying, bigger size, no mana needed) and worse (just once per turn)
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