Spells you control can't be countered. At the beginning of your end step, discover 5. (Exile cards from the top of your library until you exile a nonland card with mana value 5 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Artifacts you control have indestructible. (Effects that say "destroy" don't destroy them. Artifact creatures with indestructible can't be destroyed by damage.)

{T}: Create a 1/1 colorless Myr artifact creature token. {T}, Tap five untapped Myr you control: Search your library for a Myr creature card, put it onto the battlefield, then shuffle.

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.) Equip {1}

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.

Untap all artifacts you control during each other player's untap step.

Other artifact creatures you control have haste. Whenever one or more artifact creatures you control attack, Alibou, Ancient Witness deals X damage to any target and you scry X, where X is the number of tapped artifacts you control.

{T}: Add one mana of any color.

Creature tokens you control have haste. At the beginning of combat on your turn, create a 2/1 blue Phyrexian Myr artifact creature token. Then you may choose a token you control. If you do, each other token you control becomes a copy of that token.

{T}: Add {G}.

Indestructible (Damage and effects that say "destroy" don't destroy this creature. If its toughness is 0 or less, it's still put into its owner's graveyard.)

Artifact spells you cast cost {1} less to cast.

Artifact spells you cast cost {1} less to cast.

{T}: Add {W}.

Flying, vigilance

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.) Whenever Ichorclaw Myr becomes blocked, it gets +2/+2 until end of turn.

{T}: Add {R}.

Whenever you cast a historic spell, draw a card. (Artifacts, legendaries, and Sagas are historic.)

{2}{W}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.) Whenever one or more +1/+1 counters are put on Knighted Myr, it gains double strike until end of turn.

{T}: Add {B}.

Trample Tap an untapped artifact you control: Lodestone Myr gets +1/+1 until end of turn.

Prevent all combat damage that would be dealt to attacking artifact creatures you control. Whenever one or more artifact creatures enter the battlefield under your control, draw a card. This ability triggers only once each turn.

When Myr Battlesphere enters the battlefield, create four 1/1 colorless Myr artifact creature tokens. Whenever Myr Battlesphere attacks, you may tap X untapped Myr you control. If you do, Myr Battlesphere gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.) {T}, Pay 2 life: Add one mana of any color.

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)

Other Myr creatures you control get +1/+1. {1}, {T}: Untap each other Myr you control.

When Myr Kinsmith enters the battlefield, you may search your library for a Myr card, reveal it, put it into your hand, then shuffle.

{3}, {T}: Create a token that's a copy of Myr Propagator.

When Myr Retriever dies, return another target artifact card from your graveyard to your hand.

When Myr Sire dies, create a 1/1 colorless Phyrexian Myr artifact creature token.

Spend only mana produced by creatures to cast this spell.

Imprint — {T}: Exile target artifact card from a graveyard. Myr Welder has all activated abilities of all cards exiled with it.

Whenever you cast an artifact spell, you may pay {1}. If you do, create a 1/1 colorless Myr artifact creature token.

Artifacts you control have hexproof. At the beginning of your upkeep, if you control the artifact with the highest mana value or tied for the highest mana value, draw a card.

{T}: Add {C}{C}.

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.) {T}: Add {C}.

Ward {2} As Roaming Throne enters the battlefield, choose a creature type. Roaming Throne is the chosen type in addition to its other types. If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Flash You may cast artifact spells as though they had flash.

{T}: Add {U}.

{T}: Put a +1/+1 counter on each artifact creature you control.

Creatures you control have "{T}: Add one mana of any color."

You may look at the top card of your library any time. You may cast creature spells from the top of your library. Creatures you control have "{T}: Add one mana of any color."

As Kindred Discovery enters the battlefield, choose a creature type. Whenever a creature you control of the chosen type enters the battlefield or attacks, draw a card.

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Counter target spell.

Tap target creature. Metalcraft — If you control three or more artifacts, exile that creature.

Search your library for an artifact or enchantment card, reveal it, then shuffle and put that card on top.

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Permanents you control gain hexproof and indestructible until end of turn.

Create two 1/1 colorless Myr artifact creature tokens.

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

{T}: Add {C}. {1}{U}, {T}: Put target artifact card from your graveyard on top of your library.

{T}: Add {W}.

({T}: Add {G} or {U}.) As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

{T}: Add {C}. {2}, {T}, Sacrifice Buried Ruin: Return target artifact card from your graveyard to your hand.

Indestructible {T}: Add {C}. {5}, {T}: Add five mana in any combination of colors.

{T}: Add one mana of any color in your commander's color identity.

Darkmoss Bridge enters the battlefield tapped. Indestructible {T}: Add {B} or {G}.

Indestructible {T}: Add {C}.

Drossforge Bridge enters the battlefield tapped. Indestructible {T}: Add {B} or {R}.

{T}: Add one mana of any color that a land an opponent controls could produce.

({T}: Add {W} or {B}.) As Godless Shrine enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Goldmire Bridge enters the battlefield tapped. Indestructible {T}: Add {W} or {B}.

{T}: Add {R}.

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

At the beginning of your upkeep, if you control three or more artifacts, you gain 1 life. {T}: Add {C}. {4}, {T}, Sacrifice Inventors' Fair: Search your library for an artifact card, reveal it, put it into your hand, then shuffle. Activate only if you control three or more artifacts.

Mistvault Bridge enters the battlefield tapped. Indestructible {T}: Add {U} or {B}.

({T}: Add {B} or {G}.) As Overgrown Tomb enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Path of Ancestry enters the battlefield tapped. {T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Razortide Bridge enters the battlefield tapped. Indestructible {T}: Add {W} or {U}.

You have no maximum hand size. {T}: Add {C}.

{T}: Add {C}. {4}, {T}: Target creature can't be blocked this turn.

Rustvale Bridge enters the battlefield tapped. Indestructible {T}: Add {R} or {W}.

({T}: Add {R} or {W}.) As Sacred Foundry enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

{T}: Add {U}.

Silverbluff Bridge enters the battlefield tapped. Indestructible {T}: Add {U} or {R}.

Slagwoods Bridge enters the battlefield tapped. Indestructible {T}: Add {R} or {G}.

({T}: Add {U} or {R}.) As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

({T}: Add {R} or {G}.) As Stomping Ground enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Tanglepool Bridge enters the battlefield tapped. Indestructible {T}: Add {G} or {U}.

({T}: Add {G} or {W}.) As Temple Garden enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

The World Tree enters the battlefield tapped. {T}: Add {G}. As long as you control six or more lands, lands you control have "{T}: Add one mana of any color." {W}{W}{U}{U}{B}{B}{R}{R}{G}{G}, {T}, Sacrifice The World Tree: Search your library for any number of God cards, put them onto the battlefield, then shuffle.

Thornglint Bridge enters the battlefield tapped. Indestructible {T}: Add {G} or {W}.

{T}: Add {C}. {2}, {T}: You gain 1 life for each colorless creature you control.

{T}: Add {G}.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Urza's Saga gains "{T}: Add {C}." II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature 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.

{T}: Add {B}.

Each player sacrifices all permanents they control that are one or more colors.

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.) Destroy all nonartifact creatures.

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.) Draw two cards.