Decision Paralysis

The skipped untap step is the whole point, and it is the only thing separating this from a vanilla double-tap. A one-turn tap is trivially recovered; pinning a creature through its controller's next untap keeps it dark across two full turns, long enough to peel a blocker or a racer off the board for the swing that actually decides things. The rate is where it struggles. Four mana buys a lockdown that alters nothing permanent, competing for a slot that hard removal, which simply deletes the threat, usually claims. What it offers instead is timing. Cast at the end of an opponent's turn to strip two would-be blockers before your own attack; held up, it threatens to freeze the creatures a tempo deck is banking on. It even functions against attackers already declared and tapped in combat: the tap does nothing there, but the untap-denial still resolves, locking those creatures out of their controller's next turn, so a defensive cast still buys you a clean crackback the following turn. It reads like a two-target extension of Frost Breath, but the added reach does not buy card advantage, only tempo, which is the trade blue accepts when it cannot afford to trade card for card.