Redcap Gutter-Dweller

Menace
When this creature enters, create two 1/1 black Rat creature tokens with "This token can't block."
At the beginning of your upkeep, you may sacrifice another creature. If you do, put a +1/+1 counter on this creature and exile the top card of your library. You may play that card this turn.

Foundations

Wilds of Eldraine

Menace
When Redcap Gutter-Dweller enters the battlefield, create two 1/1 black Rat creature tokens with "This creature can't block."
At the beginning of your upkeep, you may sacrifice another creature. If you do, put a +1/+1 counter on Redcap Gutter-Dweller and exile the top card of your library. You may play that card this turn.

Wilds of Eldraine Promos

If Redcap Gutter-Dweller leaves the battlefield after its last ability has triggered, you can still sacrifice a creature and exile the top card of your library, even though you won't put a +1/+1 counter on Redcap Gutter-Dweller.

You pay all costs and follow all normal timing rules for cards played with the permission granted by Redcap Gutter-Dweller's last ability. For example, if the exiled card is a land card, you may play it only during your main phase while the stack is empty.