Score from a rehearsed corner. Set a legal block with the front man of the train, peel the runner off it into the space, and deliver a low driven ball for a first-time finish within four seconds.
Line the attackers up in a train in front of goal. On the call, the front man blocks the markers' path (body in the way, no arms) while the player behind peels off him into the space. The taker drives the corner low and flat for a first-time finish. Have two or three options off the same shape depending on how the defence sets up, and take it inside four seconds.
Defenders cannot mark a run they have not seen developing, and the train exists to delay the moment they see it. Four players standing in single file on the edge of the area present a defence with one problem instead of four, because until they break off in different directions there is nothing to pick up. In a court-sized space where defenders have almost no recovery distance, half a second of confusion is the entire margin.
That is a basketball idea and futsal borrows it openly. The front man of the train is not attacking the ball at all. His job is to stand still in the path of the defender who would otherwise track the runner behind him. The runner's timing is what makes it work: leaving too early means arriving before the block is set, and the routine collapses into two teammates colliding.
The delivery has to be low and driven. Futsal ceilings and futsal goals both punish a floated ball, and a low delivery across the face gives a runner arriving off a block something he can redirect with one touch rather than something he has to control.
Two honest warnings. The block must be a stationary body with the arms in, since moving into a defender or using the hands is a foul, and fouls accumulate in futsal until they eventually gift the opposition a ten-metre free kick. And a rehearsed corner works until the opposition has seen it twice, so carry a second option off the same shape and use it early rather than saving it.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.