Attack at speed against a set defence and finish before it recovers, and on the other side of it, defend a 3v2 while outnumbered and tired. The relentless turnover of waves is the point: decisions have to be made quickly because there is no rest between them.
Half a pitch, full goal, keeper. Two defenders start on markers near the edge of the box. Split everyone else into waves of three on the halfway line. On the call, the first wave attacks 3v2. The attack ends on a goal, a clearance, or the ball leaving the area, and the next wave goes immediately, so the defenders never get a breather. Rotate the defending pair every few waves, and make sure every player defends as well as attacks. Keep a strict tempo: if a wave is still tidying up when the next one is called, send the next one anyway. That is what the drill is for.
Twelve players and one ball is a queueing problem before it is a coaching problem. Most large-group drills spend more of their minutes on players standing in a line than on players doing anything, and the standing is where attention and behaviour go. Waves fix that by sending a new group in constantly, and that is the honest reason to pick the format.
What you get in exchange is intensity and volume. An attacking group goes in against a set defence, and on the turnover they immediately defend a counter while tired. Attacking and then defending with no reset in between is what a match actually feels like, and drills that stop and restart between phases never produce it.
The trade-off should be stated because it is real. Coaching quality per player is low here. With twelve players moving continuously you cannot stop to correct one player's body shape without eleven others waiting, so this is a format for rehearsing things players already understand rather than for teaching a new concept. Introduce the idea somewhere smaller and use waves to load it.
Two things to watch while it runs. The attacking group that slows down to organise has already lost, because the defence is set and the entire point of arriving in waves is arriving before it is. And the free man is nearly always the player furthest from the ball, which is precisely the player nobody looks for when they are tired.
Keep the groups small and the rest genuinely short. The moment players get a full recovery between waves, the format has become an ordinary attacking drill with a longer queue.
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.