Monastery Siege

The “Dragons” ability adds {2} per spell, not per target. It won’t cause a spell to cost more than {2} more to cast, even if that spell targets you and a permanent you control or more than one permanent you control.

The “Khans” ability happens after you draw the card you normally draw during your draw step. That card and the additional card will be in your hand when you have to discard a card.

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.