Scrap Trawler

Whenever this creature dies or another artifact you control is put into a graveyard from the battlefield, return to your hand target artifact card in your graveyard with lesser mana value.

March of the Machine Commander

Whenever Scrap Trawler or another artifact you control is put into a graveyard from the battlefield, return to your hand target artifact card in your graveyard with lesser mana value.

The Brothers' War Retro Artifacts

Commander 2021

If Scrap Trawler and another artifact you control are put into a graveyard at the same time, Scrap Trawler's ability triggers for each of them.

If an artifact is a copy of another artifact with greater mana value, such as Sculpting Steel copying an artifact with mana value 4, Scrap Trawler's ability can target that artifact card in your graveyard when that artifact is put into your graveyard.

The target artifact card must have a lesser mana value than the artifact that caused Scrap Trawler's ability to trigger by being put into a graveyard. Use the artifact's mana value as it last existed on the battlefield to determine what may be returned.