Sol Ring

Kormus Bell

All Swamps are 1/1 black creatures that are still lands.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Fractured Identity

Exile target nonland permanent. Each player other than its controller creates a token that's a copy of it.

Phage the Untouchable

When Phage the Untouchable enters, if you didn't cast it from your hand, you lose the game.
Whenever Phage deals combat damage to a creature, destroy that creature. It can't be regenerated.
Whenever Phage deals combat damage to a player, that player loses the game.

Swamp

Island

Toxrill, the Corrosive

At the beginning of each end step, put a slime counter on each creature you don't control.
Creatures you don't control get -1/-1 for each slime counter on them.
Whenever a creature you don't control with a slime counter on it dies, create a 1/1 black Slug creature token.
{U}{B}, Sacrifice a Slug: Draw a card.