Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. Underground River deals 1 damage to you.

Death Pits of Rath

Whenever a creature is dealt damage, destroy it. It can't be regenerated.

Fetid Heath

{T}: Add {C}.
{W/B}, {T}: Add {W}{W}, {W}{B}, or {B}{B}.

Graven Cairns

{T}: Add {C}.
{B/R}, {T}: Add {B}{B}, {B}{R}, or {R}{R}.

High Market

{T}: Add {C}.
{T}, Sacrifice a creature: You gain 1 life.

Aurification

Whenever a creature deals damage to you, put a gold counter on it.
Each creature with a gold counter on it is a Wall in addition to its other creature types and has defender. (Those creatures can't attack.)
When Aurification leaves the battlefield, remove all gold counters from all creatures.

Muddle the Mixture

Counter target instant or sorcery spell.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)