Hedron Rover

Colorless landfall is the experiment here. Most cards that scale off lands hitting the battlefield live in green, or in a specific color identity that defines the deck around them; this one strips the trigger down to its mechanical core and bolts it onto an artifact body, so any deck running it pays nothing in color commitment. The cost is that the rate is bland by default: a 2/2 for four that does nothing until a land arrives, and only swings as a 4/4 the turn it does. That makes it a creature whose threat assessment shifts entirely with the turn cycle. With no land drop it attacks as a 2/2 and trades down; with a fetch effect or an extra land in hand it hits for four in combat, and stacking multiple land entries in one turn pushes it higher still. The +2/+2 lasting until end of turn is the discipline that keeps it from snowballing: you cannot bank the growth across turns, so each attack is only as big as that turn's land drops, and you have to hold a land in reserve rather than spending your sequence early when the board is quiet. A land played in the pre-combat main phase buffs the swing just fine; the demand is timing it for a turn the attack matters, not throwing the trigger away when there is nothing worth hitting.