The cheap sends between bosses.
A tax on their attention
Nearly invisible in flight, it attaches to the first wall it reaches and becomes an emplacement whose hitscan nobody can dodge. Rocks are cover, it crawls along its wall toward anyone in reach, and their own fire is what kills it.
Finds them, then sends the swarm
Flies dead straight the way you threw it and bounces off their walls, scanning a disc wider than the last each time. Anyone it catches gets a swarm of Sweeper Drones locked on, and it keeps going until they shoot it down.
A world full of small problems
Bursts into a ring of small craft that fly straight out and bounce off their walls, each one diving onto the first ship it sees and spending itself on a hit that slows it. A ship at full speed can outrun one until it gives up, but a hit or two and the rest catch up. One bullet kills any of them, but ignored, they are still out there, waiting for whoever flies by.
Robs them on the way home
Four small ships come through, unseen until they are close, and each goes for the richest ship still carrying. One that reaches a hull clamps on and drains its hold in seconds — its host cannot shoot it, only a teammate can, and banking the rest at the gate or a stun buys time. It flees with what it took, which goes into your bank if it gets away, and killed, it drops it all.
Takes their hands, not their ships
Announces itself the moment it arrives — a blue warhead, a ring at its true blast radius and a countdown — and brakes as it flies, so the charge is the aim: a tap goes off at their gate, a full hold deep in their world. Nothing dies, but every player inside is Scrambled — left and right swapped, every ability refused — and every weapon package they carry is destroyed; it is not damage, so nothing mitigates it. Every enemy inside is stunned, a boss included, and it is live from the throw: miss your gate and it goes off in your own world, on your own field and your own team's hands.