A famous deck based on Ichorid originated from this concept.

One of the most popular uses of dredge is to use it to quickly fill your graveyard. You can't use dredge unless you're going to draw a card and the card with dredge is already in your graveyard.Once you decide to replace a draw using a card's dredge ability, that card can't be removed from your graveyard 'in response' (replacement effects don't use the stack).Dredge lets you replace any card draw, not just the one during your draw step.702.52b A player with fewer cards in their library than the number required by a dredge ability can’t mill any of them this way.“Dredge N” means “As long as you have at least N cards in your library, if you would draw a card, you may instead mill N cards and return this card from your graveyard to your hand.”

702.52a Dredge is a static ability that functions only while the card with dredge is in a player’s graveyard.From the Comprehensive Rules (June 16, 2023- The Lord of the Rings: Tales of Middle-earth)

What is the meaning of dredge