The Hidden Temple of Knowledge

{t}, add any combination of 3 basic mana
to your mana pool ({w},{u},{b},{r},{g})
This may be done once every four turns, and this
land stays tapped until the untap phase of the
fourth turn.
{t}, {4}{u}{r} Create a Knowledge token.
You can sacrifice this knowledge token at any
time to play three instant or sorcery cards
from target opponent's graveyard. Exile those
cards once they resolve.