Grand Arbiter Augustin IV
Legendary Creature — Human Advisor
White spells you cast cost 
less to cast.
Blue spells you cast cost less to cast.
Spells your opponents cast cost more to cast.
The Arbiter is a conduit of justice, a will so disciplined that it dispenses justice without ego or remorse.
2/3
Illustrated by
Modern Masters#176RareEnglishLegality
Rulings
May 1, 2006
Spells you cast that are both blue and white cost less to cast.
May 1, 2006
This reduces only generic mana portion of mana costs. A spell you cast with mana cost will cost to cast.