Aven Sentry
Filler does necessary work, and this is filler doing exactly that. The evasive white flier for four mana is one of the oldest fixtures in the common slot: a body that threatens a real clock in the air without asking the deck to bend around it, and plain enough that nobody has to read it twice. What defines this particular version is the absence of any rider at all. No text past the keyword, no tension to resolve, just a 3/2 that flies. The toughness of 2 is the honest half of the bargain: it trades up against nothing, dies to almost any damage-based answer, and survives combat against a flier only when that flier is small enough to bounce off it. That fragility is the price the rate pays for. A 3/2 flier for four is squarely fair, not a bargain, and the design leans into it: the card exists to convert an unblocked attack into pressure on a life total, three damage at a time, then get outclassed the moment the game slows down enough for the opponent to answer it. It belongs to a category white has always kept stocked: unglamorous evasive commons whose job is to close the gap in the air while the rarer cards do the heavy lifting. The design does one thing, does it cleanly, and gets out of the way.

