Like units, sites remain in play until killed, and take up two unit spots on the field.
Each site has a durability number, a static effect while it's in play, and an agenda. Agendas can create and play multiple spells across several turns, and plays a Hero unit if the site isn't destroyed quickly!
Sites are generally played from the hand, like units.[Note 1] Once played, sites enter the play zone, taking two unit spots on the field. If the site would exceed the unit spot cap (each player has a maximum of 12 unit spots), playing it prompts the player to sacrifice down to 10 units.
Each player may have only one site in play. Playing another site (even if it's different), causes the first site to be sacrificed.
While in play, each site provides an ongoing static effect to its owner.
Each site has an agenda effect listing three spells and a Hero unit. Immediately after the site is played, it prompts the player to choose one of the agenda's spells, then creates and plays it for free. At the start of the following two turns, the player is again prompted to play a previously unchosen spell. Each time one of these spells is played, a marker is placed the site to signify the agenda's advancement.
The agenda's Hero unit is played at the start of the turn after the final spell has been chosen, completing the agenda. If playing the Hero exceeds the unit cap, the player is prompted to sacrifice a unit. After the agenda is completed, the site remains in play providing its static effect.
Interacting with Sites
Sites remain in play until they are sacrificed or killed. Sites are killed when damage reduces their durability to 0. Like armor, damage to durability is permanent and doesn't reset as turns end. Scarce few cards directly kill sites, the most known examples being Icaria, First Reaper and Cremate. One of these cards is a site itself.
Players may try to damage the opponent's site by attacking it with units. This works the same as attacking a player directly, but only the opponent or their site may be attacked on a given turn, not both. When choosing attackers while the opponent has a site, the active player is prompted to choose which to attack. The defending player may then choose to block. Damage from unblocked units or Overwhelm is applied to the site's durability.
Sites can also be damaged by spells or abilities that may target them. Cards that deal damage directly to any enemy (like Signal Flare or Molot & Nakova) can damage sites. Note that some spells (such as Torch and Obliterate) may only target units or players. Some spells directly mention sites like Casualties of the Cause and Solar Blast.
As of Revelations is the only faction that doesn't have a card to deal with sites and is forced to kill it with attacking units. Derry Cathain, Ripclaw Rider can delay the site from being played by one turn.
If a berserked unit attacks a site, it will attack the site again with its second attack. However, if the site dies in the first attack, the unit attacks the player with its second attack instead.
If a site is killed by damage from a unit or spell with Overwhelm, additional damage after the site's durability is reduced to 0 is not done to the site's owner—it is absorbed by the site instead.
Similarly, if the site is attacked but it is killed before battle damage (by a fast spell, or an ability like Xo's), the attacking units' unblocked damage is still absorbed (rather than damaging the player).
If an agenda spell has no valid targets, it must still be chosen but will have no effect and the created spell card is discarded instead. The agenda is still advanced and that spell may not be chosen in future turns. This is also true if the spell cannot be played because of an effect like Svetya, Orene of Kosul.
- DWD News - Defiance: Sites! (December 07, 2018)