Your “opening hand” is the hand of cards you decide to start the game with after taking any mulligans.

After all players have decided not to take any more mulligans, if the starting player has any cards that allow actions to be taken with them from a player’s opening hand, that player may take the actions of any of those cards. The starting player repeats this, taking all actions he or she wishes to, one at a time. Then each other player in turn order may do the same. After each player has exercised his or her option to take actions from his or her opening hand, the first turn of the game begins.

If you reveal more than one Chancellor of the Spires from your opening hand, each opponent will put the top seven cards of his or her library into his or her graveyard that many times (for a total of fourteen, twenty-one, or twenty-eight cards).

The instant or sorcery card you target with the enters-the-battlefield triggered ability is cast as part of the resolution of that ability. Timing restrictions based on the card’s type are ignored. Other restrictions, such as “Cast [this card] only during combat,” are not.

If you are unable to cast the card, perhaps because there are no legal targets available, the card remains in its owner’s graveyard.

You may pay additional costs, such as kicker costs, of the instant or sorcery card.

If the card has any mandatory additional costs, then you must pay them in order to cast the spell.