Elusive Spellfist

Three toughness is the load-bearing number here, and it explains everything about how this creature is meant to be built. The evasion and the growth are both rented one spell at a time, useless on an empty turn and lethal on a full one, so the body needs to survive the turns when the engine isn't spinning. A wall that blocks all day is exactly what you want in the seat behind a deck of cantrips, cheap removal, and burn: something that trades poorly on defense but converts instantly once the noncreature spells start flowing. The trigger keys off casting, not resolution, and it stacks, so a turn with two or three spells makes the Monk both larger and unblockable, a body the opponent would happily chump-trade turned into damage they cannot stop. The unblockable clause is the half that matters more than the power bump, since evasion is what makes a small, spell-fueled clock lethal rather than merely inconvenient. This is spells-matter aggro in its most honest form: the payoff scales with spell density rather than any single big finisher, and the deckbuilding question it asks is not "what's my bomb" but "how many cheap spells can I chain in a turn." Empty hand, and it's a defensive stopgap; full hand, and it walks past the board for the last few points.