Dramatic Reversal untaps every nonland permanent you control for two mana. Mana rocks, mana creatures, utility creatures, and attacking creatures can all benefit from the same instant, giving it applications beyond a single combo. Its strongest turns come when the permanents you untap produce more value than the mana spent casting the spell.
Isochron Scepter is the best-known partner. Imprint Dramatic Reversal on the Scepter, then use nonland mana sources to pay for repeated activations. The copied Reversal untaps both the Scepter and those mana sources. If the sources produce more than the two mana needed per activation, the sequence can generate increasing amounts of mana; exactly two mana sustains repetition but does not create a net mana gain.
Outside that loop, Reversal can refresh an artifact-heavy board after you have committed mana to another spell. A blue-green deck can untap mana creatures, while an artifact creature deck can reuse Steel Overseer. It can also untap creatures after combat so they are available to block, though creatures affected by summoning sickness still cannot use tap-symbol abilities merely because they became untapped.
Count the actual output of your permanents before building a turn around the card. Lands do not untap, so a mostly land-based mana engine receives little direct help. Reversal earns its place when multiple nonland permanents have productive tap abilities or when the Scepter interaction is an intentional part of your deck.
