mtg.wtf

{T}: Add {C}.
{5}, {T}, Exile Underdark Rift: Roll a d10. Put target artifact, creature, or planeswalker into its owner's library just beneath the top X cards of that library, where X is the result. Activate only as a sorcery.

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to pay Un-costs.

Underground Mortuary enters tapped.
When Underground Mortuary enters, surveil 1.

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

Undergrowth Stadium enters tapped unless you have two or more opponents.
{T}: Add {B} or {G}.

{T}: Add one mana of any color. During your next untap step, as you untap your permanents, return Undiscovered Paradise to its owner's hand.

Hidden agenda
You may spend mana as though it were mana of any color to cast spells with the chosen name.

{TK}{TK} — {T}: Add {2}. Spend this mana only to cast creature spells.
{TK}{TK}{TK}{TK} — At the beginning of combat on your turn, target noncreature artifact you control becomes a 4/4 artifact creature with flying until end of turn.
{TK}{TK} — 2/4
{TK}{TK}{TK}{TK}{TK} — 8/6

Unhallowed Cathar can't block.

{TK}{TK} — {T}: You gain 1 life.
{TK}{TK}{TK}{TK} — Whenever this creature attacks, tap each creature an opponent controls with the same power and/or same toughness as this creature.
{TK}{TK} — 4/1
{TK}{TK}{TK} — 2/6

Black legendary creatures you control have "bands with other legendary creatures."

At the beginning of your end step, you lose 1 life.

{T}: Add {C}.
{B}, {T}: Put target Zombie card from your graveyard on top of your library.

Unified Lunge deals X damage to each player, where X is the number of Heads on the battlefield.

Unimpeded Trespasser can't be blocked.

{TK}{TK} — {T}: Add one mana of any color.
{TK}{TK}{TK} — Whenever this creature attacks, if it's not a Brushwagg, it gets +X/+0 until end of turn, where X is the number of supertypes, card types, and subtypes it has.
{TK}{TK} — 5/1
{TK}{TK}{TK}{TK} — 4/8

When you encounter this, Each player opens a Magic the Gathering booster pack. They may select up to two cards from that pack and exile them face down. For the rest of the game, players may look at and play cards exiled this way without paying their mana costs. (Then Planeswalk away from this phenomenon.)

When building your deck, choose white, blue, black, red, or green (Circle it to indicate your selection.)
{T}: Add one mana of the chosen color.
{1}, {T}: Add 1 mana of any color.

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

When you encounter Unleash the Flux, each player sacrifices a nonland permanent of their choice, then you flip a coin. If you lose the flip, repeat this process.

Each Minotaur can't be blocked this turn except by two or more creatures.

{TK}{TK} — Whenever this creature attacks, bolster 1.
{TK}{TK}{TK}{TK} — Indestructible
{TK}{TK} — 3/2
{TK}{TK}{TK} — 5/4

{T}: Add {C}.
{T}: Target land you control becomes the basic land type of your choice until end of turn.

{TK}{TK} — {1}: Switch this creature's power and toughness until end of turn.
{TK}{TK}{TK}{TK} — Whenever this creature attacks, it gets +5/+5 until end of turn.
{TK}{TK} — 3/2
{TK}{TK}{TK} — 2/7