Maritime Guard
The 1/3 for two has been the core-set wall for as long as core sets have needed one: a body that survives the small burn and the early bites, holds the ground against the format's two-power aggressors, and kills the 2/1s outright while bouncing harmlessly off the 2/2s. The toughness is the whole job. Three points keeps it alive through the chip damage a slower deck would otherwise pay in life, and the single power means it will never threaten to close a game on its own, which is precisely what a card built to buy time for a control deck's real plan is supposed to do. Merfolk and Soldier are the kind of creature types stamped onto a vanilla blue blocker so a future tribal payoff has something to count, not because this card was ever meant to anchor either line. What it represents is a recurring slot in blue's design language: the cheap, expendable ground-holder that lets an expensive deck reach its expensive spells, the stripped-down heir to Wall of Air and the long lineage of toughness-forward blockers reduced to their minimum viable form. Nothing here rewards a second look, and nothing is meant to. It is fixed-cost defense at common rarity, doing exactly the unglamorous work the curve assigned it.

