"It has been my honor to improve on Thran's original design. Perhaps history will remember me in some small part for my work." —Urza, in his apprenticeship
As Primal Clay enters the battlefield, it becomes your choice of a 3/3 artifact creature, a 2/2 artifact creature with flying, or a 1/6 Wall artifact creature with defender in addition to its other types.
{4}, {T}: Create a 1/1 colorless Snake artifact creature token. It has "Whenever this creature deals damage to a player, that player gets a poison counter."
As Shapeshifter enters the battlefield, choose a number between 0 and 7. At the beginning of your upkeep, you may choose a number between 0 and 7. Shapeshifter's power is equal to the last chosen number and its toughness is equal to 7 minus that number.
{1}, {T}, Sacrifice a creature: Skull Catapult deals 2 damage to any target.
"Let any who doubt the evil of using the ancient devices look at this infernal machine. What manner of fiend would design such a sadistic device?" —Sorine Relicbane, Soldevi heretic
You may choose not to untap Tawnos's Weaponry during your untap step. {2}, {T}: Target creature gets +1/+1 for as long as Tawnos's Weaponry remains tapped.
When war machines became too costly, Tawnos's weaponry replaced them.
At the beginning of your upkeep, put a time counter on Time Bomb. {1}, {T}, Sacrifice Time Bomb: Time Bomb deals damage equal to the number of time counters on it to each creature and each player.
Even the most conservative generals revised their tactics after the Battle of Sarinth, during which a handful of peasant-pikemen held off a trio of rampaging craw wurms.
As long as Winter Orb is untapped, players can't untap more than one land during their untap steps.
"When once winter has ahold, Not willingly does she withdraw Her icy touch, wistfully caressing— The deepened air sleeps its cold." —Aline Corralurn, "Late Thaw"
Bottomless Vault enters the battlefield tapped. You may choose not to untap Bottomless Vault during your untap step. At the beginning of your upkeep, if Bottomless Vault is tapped, put a storage counter on it. {T}, Remove any number of storage counters from Bottomless Vault: Add {B} for each storage counter removed this way.
Dwarven Hold enters the battlefield tapped. You may choose not to untap Dwarven Hold during your untap step. At the beginning of your upkeep, if Dwarven Hold is tapped, put a storage counter on it. {T}, Remove any number of storage counters from Dwarven Hold: Add {R} for each storage counter removed this way.