The well

When The well enters the battlefield, you gain {x} life, where {x} is the
amount of mana tapped to play this card
{x}{u/b}, your opponent discards the top {x} cards of his/her library, where {x} is the amount
of mana tapped
{x}{u/b}, you gain {x} life, where {x} is the amount
of mana tapped
{t}, draw 4 cards