As Outpost Siege enters the battlefield, choose Khans or Dragons.
• Khans — At the beginning of your upkeep, exile the top card of your library. Until end of turn, you may play that card.
• Dragons — Whenever a creature you control leaves the battlefield, Outpost Siege deals 1 damage to any target.
The card exiled by the “Khans” ability is exiled face up. Playing a card exiled with the “Khans” ability follows the normal rules for playing the card. You must pay its costs, and you must follow all applicable timing rules. For example, if it’s a creature card, you can cast it only during your main phase while the stack is empty.
If you exile a land card using the “Khans” ability, you may play that land only if you have any available land plays. Normally, this means you can play the land only if you haven’t played a land yet that turn.
If a noncreature card is manifested and then leaves the battlefield while face down, the “Dragons” ability will trigger.
Each Siege will have one of the two listed abilities, depending on your choice as it enters the battlefield.
The words “Khans” and “Dragons” are anchor words, connecting your choice to the appropriate ability. Anchor words are a new rules concept. “[Anchor word] — [Ability]” means “As long as you chose [anchor word] as this permanent entered the battlefield, this permanent has [ability].” Notably, the anchor word “Dragons” has no connection to the creature type Dragon.
Each of the last two abilities is linked to the first ability. They each refer only to the choice made as a result of the first ability. If a permanent enters the battlefield as a copy of one of the Sieges, its controller will make a new choice for that Siege. Which ability the copy has won’t depend on the choice made for the original permanent.