Icefall Regent

A flying body that arrives and locks down the most threatening thing across the table, then dares your opponent to spend extra mana for the privilege of removing it. The enters-tapped clause is not a one-turn Frost Breath: the target stays tapped for as long as the Regent survives, which turns a five-mana creature into a soft Pacifism stapled to an evasive clock. That conditional is what makes the tap meaningful. Pin down a blocker and start swinging in the air, or freeze a key attacker and the lock holds until someone deals with the Dragon. The tax on opponent spells that target it is the protection layer that closes the loop: it makes the cheap removal that would otherwise undo both halves of the card meaningfully more expensive, so the lockdown tends to stick. Each ability props up the other. Tempo creatures usually trade evasion for fragility, and a 4/3 dies to most of what blue wants to tax against. Bundling the tax onto the same card that enables the lock is the design move that keeps the Regent honest as a threat rather than a glass cannon, demanding a sweeper or a sacrifice effect rather than the targeted answers blue most often invites.