The Millennium Calendar

Whenever you untap one or more permanents during your untap step, put that many time counters on The Millennium Calendar.
{2}, {T}: Double the number of time counters on The Millennium Calendar.
When there are 1,000 or more time counters on The Millennium Calendar, sacrifice it and each opponent loses 1,000 life.

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga gains "{T}: Add {C}."
II — This Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This token gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Deserted Beach

This land enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

Archmage's Charm

Choose one —
• Counter target spell.
• Target player draws two cards.
• Gain control of target nonland permanent with mana value 1 or less.

Welding Jar

Sacrifice this artifact: Regenerate target artifact.

Dress Down

Flash
When this enchantment enters, draw a card.
Creatures lose all abilities.
At the beginning of the end step, sacrifice this enchantment.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Island

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Plains

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.

Flooded Strand

{T}, Pay 1 life, Sacrifice this land: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Hallowed Fountain

({T}: Add {W} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Counterspell

Urza, Lord High Artificer

When Urza enters, create a 0/0 colorless Construct artifact creature token with "This token gets +1/+1 for each artifact you control."
Tap an untapped artifact you control: Add {U}.
{5}: Shuffle your library, then exile the top card. Until end of turn, you may play that card without paying its mana cost.

Ethersworn Canonist

Each player who has cast a nonartifact spell this turn can't cast additional nonartifact spells.

Prismatic Ending

Converge — Exile target nonland permanent if its mana value is less than or equal to the number of colors of mana spent to cast this spell.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is this creature's power.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Seachrome Coast

This land enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {U}.