"What is death?" he asked the raven.
"Your next birth," it replied.

Golgari Thug

When Golgari Thug dies, put target creature card from your graveyard on top of your library.
Dredge 4 (If you would draw a card, you may mill four cards instead. If you do, return this card from your graveyard to your hand.)

Ravnica Remastered

When Golgari Thug dies, put target creature card from your graveyard on top of your library.
Dredge 4

The List

Secret Lair Drop

Ultimate Masters

When Golgari Thug dies, put target creature card from your graveyard on top of your library.
Dredge 4 (If you would draw a card, instead you may put exactly four cards from the top of your library into your graveyard. If you do, return this card from your graveyard to your hand. Otherwise, draw a card.)

Dredge can replace any card draw, not only the one during your draw step.

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.

If you're drawing multiple cards, each draw is performed one at a time. For example, if you're instructed to draw two cards and you replace the first draw with a dredge ability, another card with a dredge ability (including one that was milled by the first dredge ability) may be used to replace the second draw.

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.

One card draw can't be replaced by multiple dredge abilities.

You can't attempt to use a dredge ability if you don't have enough cards in your library.