Rulings

• If you choose 1 for the value of X, Astral Cornucopia will cost {3} to cast and enter the battlefield with one charge counter. If you choose 2 for the value of X, it will cost {6} to cast and enter the battlefield with two charge counters, and so on.2014-02-01
• The last ability is a mana ability. It doesn't use the stack and can't be responded to.2014-02-01