One bird two stones

The user can conjure copies of stuff they’ve «launched»/«thrown».

1, the copies spawn 1 inch away from the original and their trajectory are decided upon creation

2, they have the same speed as the original

3, each projectile can spark one copy, copies cannot spark additional copies

4, copies can be created at any point during the projectiles trajectory

5, copies disappear after a minute, and share damage with their original after despawning.

The user starts off using it with a gun to double bullets or pull off trick shots, then with grenades for extra boom.

If we’re open to being wacky the user could at some point have an experience where they learn bodies are made of stuff, so they’ve made copies of themselves by launching themselves with a catapult, doubled punches by «throwing punches» and copying their arm, and judo tossed enemies, made a duplicate of them, to then explode with the same grenade to deal double damage to them.