Mana Bucket

Whenever a land card enters the battlefield, put a charge counter on Mana Bucket.
Remove a charge counter from Mana Bucket:
Spells you cast cost {1} less to cast until end of
turn.
Remove six charge counters from Mana Bucket:
Spells you cast cost {w}{u}{b}{r}{g}{2} less to cast
until end of turn.