Shalai, Voice of Plenty

The crucial word in the protective clause is "other." A blanket hexproof umbrella would shield the Angel herself and let her sit untouchable while the board hides behind her; instead she covers you, your planeswalkers, and your other creatures but not her own body, and that single exception is what stops the card from locking opponents out entirely. Kill her and the umbrella collapses, so the protection lives or dies on whether the opponent can find an answer to a 3/4 flier before it matters. The design problem is solved cleanly by that one carve-out: you get a defensive shell around your team, your face, and even your planeswalkers, but you hand the opponent exactly one target that turns all of it off. The second ability is the part players forget she carries, a late-game mana sink that reaches out of white and into green for a board-wide pump. It signals where she wants to live: in a deck patient enough to stick her, ride the protection through a few turns, and eventually empty its mana into an anthem the opponent can no longer interact with piecemeal, because every other creature receiving those counters is itself untargetable. She is a lock and a clock in one body, and the tension between her own vulnerability and her board's invulnerability is what makes her worth building around rather than merely sturdy.