Jeskai Brushmaster

Prowess resolves before combat damage, and that sequencing is what makes stapling it to double strike a multiplier rather than an addition: cast a cheap noncreature spell, the +1/+1 lands, and both hits scale off the pumped number instead of the base 2/4. One spell turns this into a 3/5 that lands six damage across the two strikes; two spells make it eight. That compounding is what justifies a three-color body at four mana whose printed stat line is otherwise unremarkable. The 4 toughness earns its keep quietly, sitting above the reach of most one-mana burn so the creature survives to the turn you assemble the spells that matter. It is a payoff built for a spells-dense tempo shell: the more of your deck is noncreature spells, the more each attack step swells, and double strike guarantees a chunk of that pump converts to actual damage rather than a bigger idle blocker. Left alone, the body is a durable blank, and it only repays its cost inside a deck with enough cheap interaction to fire prowess on the swings that count. That deckbuilding requirement is the leash keeping a double-striking prowess creature from being a free include in any three-color pile.