If you sac a myr retriever to krark clan ironworks in order to pay for something you’re casting then myr retriever is already in the graveyard when myr retriever’s trigger goes on the stack allowing it to retrieve itself. This is because the sac effect of ironworks is a mana ability and thus moves the creature you sac outside of the stack itself.
If I have to remember how layers work I scoop on principle. Same with banding.
Banding is easy. People just didn’t like it because a measly 1/1 could stop Timmy’s giant trampling green creature.
If you sac a myr retriever to krark clan ironworks in order to pay for something you’re casting then myr retriever is already in the graveyard when myr retriever’s trigger goes on the stack allowing it to retrieve itself. This is because the sac effect of ironworks is a mana ability and thus moves the creature you sac outside of the stack itself.