Excessive Knowledge

When Excessive Knowledge enters the battlefield,
each player draws 7 cards.
Whenever a player casts a spell, that player draws
a card.
Whenever an opponent discards a non-land card,
add {x} to your mana pool where {x} is the
manavalue of the discarded card.
Until the end of your next turn, you don't loose
this mana as steps and phases end.