Berta, Wise Extrapolator

The Increment keyword reads the creature's own body against every spell you cast, and the trigger is generous: it fires whenever the mana you spend beats either number, so with a 1/4 the low power figure is the threshold that matters. Because 1 is the bar to clear, almost any real spell keeps the counters coming early, and the engine only self-throttles once power has climbed past what your typical spends cost. That gap between a small power and a stubborn toughness is the design's cleverest tuning: the body survives while it grows, and the growth rate tapers on its own without any external ceiling. The mana line pays for the event of counters arriving, not their count: any single effect that lands one or more +1/+1 counters yields exactly one mana of any color, so dumping a stack at once pays the same as a lone trigger. The activated ability spends that mana straight back out, converting X into a Fractal token that arrives loaded with X counters, itself a fresh vessel for whatever else in the deck cares about them. All three lines trade in the same two currencies, counters feeding mana feeding more counters, and the apparatus scales with how expensive the deck around it wants to play. It sits at the center as both the meter reading your spells and the generator paying you for having cast them.