Swamp

Lethal Vapors

Whenever a creature enters, destroy it.
{0}: Destroy Lethal Vapors. You skip your next turn. Any player may activate this ability.

Rowan, Scion of War

Menace
{T}: Spells you cast this turn that are black and/or red cost {X} less to cast, where X is the amount of life you lost this turn. Activate only as a sorcery.

Tainted Aether

Whenever a creature enters, its controller sacrifices a creature or land of their choice.

Spreading Plague

Whenever a creature enters, destroy all other creatures that share a color with it. They can't be regenerated.

No Mercy

Whenever a creature deals damage to you, destroy it.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Tree of Perdition

Defender
{T}: Exchange target opponent's life total with Tree of Perdition's toughness.

Everlasting Torment

Players can't gain life.
Damage can't be prevented.
All damage is dealt as though its source had wither. (A source with wither deals damage to creatures in the form of -1/-1 counters.)

Mountain

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Spellshock

Whenever a player casts a spell, Spellshock deals 2 damage to that player.

Snuff Out

If you control a Swamp, you may pay 4 life rather than pay this spell's mana cost.
Destroy target nonblack creature. It can't be regenerated.