Helga, Skittish Seer

Two payoffs stapled to one small body, and the second is what turns her from a value creature into an engine you build a whole deck around. The trigger rewards a big-creatures plan the plain way: cast something with mana value 4 or greater, and she draws, gains a life, and grows. Note the word cast: she pays you at announcement, so a countered spell still nets the card and the counter. The mana ability is where the design tightens, converting that accumulated power into fuel for exactly the spells that fed her. Each fat creature you cast raises her power, and her power is the mana she taps for, so the loop feeds itself: bigger casts make more mana, which casts bigger creatures. The spend restriction is what stops her from being a generic ramp dork. The mana can only pay for creature spells at mana value 4 or greater or creature spells carrying an in their cost, so it cannot fund noncreature ramp, removal, or a fast combo. She exists to do one thing louder every turn. That -cost clause is the sharpest wrinkle, letting a grown Helga dump into hydras and other scaling threats that would otherwise sit dead in hand, translating her power total directly into their size. The small frame confirms the role: she is not an attacker but a battery that reads the top of your curve and pays you back for committing to it.