Steadfast Armasaur

Vigilance and the activated ability sit in productive tension: staying untapped through your attack step is exactly what fuels the biting attack the ability grants. Two design choices narrow the effect into a deterrent rather than a free-fire pinger. First, the damage equals toughness, not power, so the 2/3 defends harder than it swings, dealing three to whatever it is fighting. Second, the reach is confined to a creature blocking it or blocked by it, meaning combat must already be joined before it can bite anything. The result is a lane-holder that punishes aggression: an opponent who blocks it watches their blocker take three before combat damage is even assigned, and an opponent who lets it through hands you a swing plus an activation on the next turn. Most of the time the threat of the activation does the work and the mana stays open behind an untapped body. The toughness-based damage and the combat-only restriction turn a modest defender into a soft tax on attacking: it does not hunt, it waits, and it makes overcommitting into a board an opponent should have left alone cost a creature. Plain in its role, but cleanly built around the friction between holding the ground untapped and spending that untapped status to bite whatever steps into the combat with it.