Returning is a behaviour a projectile can have to continue travelling after a hit, like pierce, fork and chain. The projectiles will return if they hit a target and do not pierce/fork/chain from them. If they pierce/fork/chain, they cannot return on that target (but can on future targets if they don't pierce/fork/chain on those). Once it's hit one target, a regular projectile cannot hit the same target again.
Return is a behavior of projectiles that causes them to attempt to return to the entity that fired them after they hit a target.
Only one projectile behavior can be applied each time a projectile hits a target. Return has fifth priority for projectile behaviors, preceded by Split, pierce, fork and chain.
When a projectile returns, it bounces off the target it hits and continues in the direction of the entity that fired it. If the entity that fired the projectile no longer exists—as is the case if it was fired by a trap or mine—the projectile will attempt to return to the last known location of the firing entity. A projectile can only return once. Returning projectiles can hit a previously hit target; however, only a single projectile from a single skill use can hit during the return (subsequent returning hits will pass through the monster and not deal damage).
Projectiles apply their on-hit effects to each target they return from or otherwise hit. For example, Essence Drain will apply its debuff to each target a projectile hits. Skills such as Ice Shot and Kinetic Blast apply their on-hit area damage effects each time a projectile hits a target. The explosion behavior of some projectiles, such as Fireball and Creeping Frost, is not an on-hit effect and occurs only when a projectile ceases to exist.
Currently there are two versions of Return. One requiring a final target and one that does not. Returning projectiles that require a final target will only return when hitting an enemy and state "from final Target". Returning projectiles that do not require a final target can also return upon hitting a wall or traveling their maximum distance, on top of when hitting a target and having no higher priority projectile action (pierce, chain, etc) while simply stating "return to you".