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When R&D was working on the Sixth Edition rule change, I brought up to Bill Rose (the current vice president of R&D, who was the head designer at the time, and was the one mainly responsible for overseeing the Sixth Edition rules) that the "tapped artifacts shut off" rule was confusing, non-intuitive, and constantly causing problems
If however the spell you manage to place back on top is one that is only useful because of the stage of the game such as a ramp spell then you have gained a huge advantage, greater that you would have gotten from putting that card in the graveyard
Zabaz, the Glimmerwasp is the best one given the constraints of the deck and is a searchable Hardened Scales imitation for Arcbound Ravager or the other, more dopey modular creatures
The only drawback to its use in Standard is that it's a pricey card, costing five mana