Phyrexia's largest goliaths stormed Ikoria, ready to challenge the world's great monsters. Zilortha was unimpressed.

Invasion of Ikoria // Zilortha, Apex of Ikoria

Reach
For each non-Human creature you control, you may have that creature assign its combat damage as though it weren't blocked.

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When this Siege enters, search your library and/or graveyard for a non-Human creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle.

March of the Machine

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Ikoria enters the battlefield, search your library and/or graveyard for a non-Human creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle.

March of the Machine Promos

A Siege’s controller can’t be its protector. If a Siege’s protector ever gains control of it, they choose a new player to be its protector. This is a state-based action.

A battle can be attacked by all players other than its protector. Notably, this means a Siege’s controller can attack it.

A battle can be dealt damage and be target of spells and/or abilities that target “any target.”

A battle’s “defense” is displayed in the bottom right corner of the card. A battle enters the battlefield with that number of defense counters. If another permanent enters the battlefield as a copy of a battle, it also enters with that number of defense counters.

As a Siege enters the battlefield, its controller chooses an opponent to be its protector.

Assigning a creature’s damage as though it weren’t blocked is all or nothing. You can’t use this effect to assign some of the creature’s damage to a blocking creature and the rest to the player, planeswalker, or battle it’s attacking.

Battles can’t attack or block, even if one also becomes a creature. If an attacking or blocking creature somehow becomes a battle in addition to being a creature, it is removed from combat.

Damage dealt to a battle causes that many defense counters to be removed from it.

Even if a creature assigns damage as though it were not blocked, it will still receive damage from creatures that are blocking it.

If a Siege never had defense counters on it (perhaps because a permanent became a copy of one), it can’t have its last defense counter removed. It will be put into its owner’s graveyard. You won’t exile it or cast the other face.

If a battle has no defense counters, and it isn’t the source of a triggered ability that has triggered but not yet left the stack, that battle is put into its owner’s graveyard. This is a state-based action. This doesn’t cause a Siege’s intrinsic triggered ability to trigger.

If a battle that’s being attacked somehow stops being a battle, it is removed from combat. Similarly, if its controller changes in the middle of combat, it is removed from combat.

If a non-battle permanent that is already on the battlefield become a copy of a Siege, its controller chooses one of their opponents to be that battle’s protector. However, it will most likely be put into its owner’s graveyard because it has no defense counters (see below).

If a permanent that is represented by a transforming double-faced card becomes a copy of a Siege, it will be exiled as that Siege’s triggered ability resolves, then it will be cast transformed. Note that this applies only to transforming double-faced cards, not to modal double-faced cards that can normally be played using either face.

If a token or a card that isn’t represented by a transforming double-faced card becomes a copy of a Siege, it can’t be cast as its triggered ability resolves. It will remain in exile. If it’s a token, it will cease to exist the next time state-based actions are performed.

In a multiplayer game, if the protector of a battle leaves the game and that battle is not currently being attacked, its controller chooses a new protector for it as a state-based action. If it is being attacked, its controller chooses a new protector for it once no creatures are attacking it. This means that it continues to be attacked and can be dealt combat damage as normal.

Only creatures controlled by a battle’s protector can block creatures that are attacking that battle. This means a Siege’s controller can never assign creatures to block for it.

Sieges each have an intrinsic triggered ability. That ability is “When the last defense counter is removed from this permanent, exile it, then you may cast it transformed without paying its mana cost.”

You decide whether to assign a non-Human creature’s combat damage as though it weren’t blocked just before it assigns that damage. You may make a different choice for each non-Human creature you control—that is, you may have none, some, or all of those creatures assign combat damage as though they weren’t blocked.