Conduit of Channeling

{t}: Put Y Mana counters on Conduit of
Channeling, where Y is the mana spent this
turn. Activate this ability only on your
opponent's turn. (A Y value is basically an
X value, but it can contain a list of different
value names, each with their own value amount.)
When Conduit of Channeling dies, Add Y to
your mana pool.