2022-10-07 : If you cast a spell with {X} in its mana cost this way, the only legal choice for X is 0.

2022-10-07 : You may only cast a spell this way by paying the appropriate amount of life. You may not pay its normal cost and may not pay any other alternative costs. You may still pay for additional costs, such as kicker costs. If the spell has mandatory additional costs, you must pay those.