Daring Mechanic

The activated ability tells you the whole plan: this is a mana sink built to grow the Mounts and Vehicles that carry a mechanized aggro deck. Four mana for a single +1/+1 counter is a deliberately expensive rate, which is what keeps it honest as a late-game outlet rather than an early snowball, but the counters are permanent and stack turn after turn, so a stalled board eventually tips over under repeated activations. Because the ability carries no timing restriction, it works at instant speed: you can hold up the mana and pump a blocker mid-combat, or dump excess mana at the end of an opponent's turn without tapping out on your own. That flexibility is more valuable than the flat cost suggests, since the growth can be a combat trick as easily as a durdle-turn investment. What it will not do is generate its own board; with nothing worth targeting it is a 3/3 body and a dormant ability, which means it asks you to have already committed to Mounts and Vehicles before it earns its slot. As support for that narrow subtype plan, it fills an anthem-adjacent role without demanding a specific board state, and it does little of interest for any white deck not committed to riding into combat.