Temporal Manipulation

The clean five-mana baseline for the extra-turn effect, and the one every subsequent design has been priced against. Time Walk did this for two mana and got restricted into oblivion; the lesson Wizards took from it was that the effect itself is fine, but the rate has to hurt. Five mana at no card advantage (you draw a card on the extra turn, but the spell replaces itself, not improves your hand) is the cost that makes taking another turn a deliberate commitment rather than a free tempo swing. The design discipline here is the flat price tag with no rider: no untapping lands, no bounce, no buyback, nothing that lets the turn pay for itself. You spend the whole turn casting it, then you get one more, and the question is always whether the next turn does enough to justify having skipped this one's development. That austerity is precisely why it became the reference point. When designers wanted to push the effect, they added conditions that reward sequencing (Part the Waterveil with its awaken clause, Temporal Mastery with miracle, Nexus of Fate's shuffle-back loop); when they wanted to gate it harder, they raised the cost or attached an exile clause. Temporal Manipulation sits at the structural center of that lineage: no upside, no downside, just the effect at the number Wizards decided it was worth.