Staff of Spell Transmutation

On your turn, you may sacrifice any number of
instant or sorcery spells and put charge counters
on Staff of Spell Transmutation equal to the
converted mana cost of the spells sacrificed.
{t}: Sacrifice X charge counters and pick one;
•Deal X damage to a target of your choice.
•Counter target spell with converted mana cost X.
This artifact may be tapped at any time.