Stalked Researcher

A 3/3 for two that arrives stapled to the battlefield until you feed it. Defender on an aggressive body is the constraint, and the Eerie trigger is the release valve: build a board of enchantments and Rooms, and each one that resolves flips this into a live attacker for the turn. The design takes a familiar tension (a creature whose stats want to swing but whose keyword forbids it) and resolves it by tying combat to the deck's real engine rather than to a one-time unlock. The wrinkle worth noting is that the permission is per-turn and re-earned: attack this turn, and next turn the defender clamp snaps back on until you trigger Eerie again, so the card wants a steady drip of enchantment enters or Room unlocks rather than a single burst. That makes it less a beater than a payoff, a body that punishes an opponent for letting your enchantment count climb while sitting behind reasonable defensive stats when it can't swing. It sits at the tail of every defender-with-an-out design that has tried to justify oversized rear-facing stats: the reward for tolerating the drawback is a creature that costs less than an unconditional 3/3 attacker of the same color would, priced down precisely because the swing isn't free.