Stern Judge

{T}: Each player loses 1 life for each Swamp they control.

Urborg, Tomb of Yawgmoth

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

Preacher

You may choose not to untap this creature during your untap step.
{T}: For as long as this creature remains tapped, gain control of target creature of an opponent's choice they control.

Angry Mob

Trample
During your turn, Angry Mob's power and toughness are each equal to 2 plus the number of Swamps your opponents control. During turns other than yours, Angry Mob's power and toughness are each 2.

Karma

At the beginning of each player's upkeep, this enchantment deals damage to that player equal to the number of Swamps they control.