Bloated Toad

Protection from blue stapled to a forest creature is a thesis, not just a stat line: the Urza's block was the high-water mark of blue control, and green's answer was to print bodies the format's blue removal could not touch once they were on the battlefield. Protection from blue means the creature shrugs off Capsize, Boomerang, and the assorted blue point-removal that otherwise kept green's ground troops in check, and it cannot be chump-blocked or otherwise contained by a blue creature. The protection does nothing to save the spell from a counter on the stack, of course (a counterspell answers the frog before it ever becomes a permanent), but once it resolves it sits across the table as a body the blue mage's damage, targeting, and blockers simply cannot touch. Cycling is what stops the narrow ability from becoming a liability: when the matchup is not blue, the hate-bear half of the card is a dead 2/2, so the same card converts into a fresh draw for two generic mana. That is the structural trick worth noting. A matchup-dependent ability normally produces a card you regret drawing in the wrong game, and cycling is the release valve that lets the designer push the protection effect without saddling the player with a brick. The frog is a small, deliberate piece of the era's color-pie war, built so that its worst-case scenario is still a cantrip rather than a wasted card.