You can't attempt to use a dredge ability if you don't have enough cards in your library.
Life from the Loam
Once you've announced that you're applying a card's dredge ability to replace a draw, players can't take any actions until you've put that card into your hand and milled cards.
If an effect puts a card into your hand without specifically using the word "draw," you're not drawing a card. Dredge can't replace this event.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Terese Nielsen
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
