Svyelunite Priest

A protection effect with two restrictions stacked on top of each other, and both of them tell you something about how nervous early design was about giving blue access to shroud. The activation costs two blue mana plus the tap, on a 1/1 body that has to survive a turn before it can do anything; and even then, the window is locked to your own upkeep, which means you cannot use it reactively to blank a removal spell or save a creature mid-combat. You are committing to the protection at the start of your turn, before you know what the threat will be. That sorcery-speed-equivalent clamp is the whole balance point: instant-speed shroud-granting on a repeatable source would have been a hard counter to targeted interaction, so the card pays for the effect by surrendering the timing that would make it good. It reads as a precursor to the later, cleaner protection bodies that simply hand out hexproof or shroud at instant speed, and the contrast shows how much the cost of an effect lived in its activation window before the design language settled. What survives is a piece of historical texture: a Merfolk Cleric whose job was to telegraph your protection at the start of your turn and dare the opponent to play around it.