Urborg, Tomb of Yawgmoth

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

Kormus Bell

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

Urborg Emissary

Kicker {1}{U} (You may pay an additional {1}{U} as you cast this spell.)
When Urborg Emissary enters, if it was kicked, return target permanent to its owner's hand.

The Scarab God

At the beginning of your upkeep, each opponent loses X life and you scry X, where X is the number of Zombies you control.
{2}{U}{B}: Exile target creature card from a graveyard. Create a token that's a copy of it, except it's a 4/4 black Zombie.
When The Scarab God dies, return it to its owner's hand at the beginning of the next end step.

Urborg

{T}: Add {B}.
{T}: Target creature loses first strike or swampwalk until end of turn.

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.