Sorcery, UU (2) Target player plays a mana ability of each land he or she controls, then empties his or her mana pool. Add mana to your mana pool equal to the type and amount emptied from that player's mana pool this way.1
Illus. Douglas Shuler
Since this is a sorcery, your opponent may use instants and abilities of permanents in response to this spell before you get the mana from their mana pool and lands. [D'Angelo 2000/03/03]
If a land can draw more than one color of mana (by choice) then the target player (not the caster of this spell) chooses which colors are drawn at the time they draw it. [bethmo 1994/06/01]
If a land can draw a variable amount of mana, the target player (not the caster of this spell) chooses how much to draw. [D'Angelo 2002/07/21]