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.
To be Arbiter is to dispense few words and many judgments.
Greg Hildebrandt
Double Masters 2022 (2X2)
• #379Rulings
This reduces only generic mana portion of mana costs. A spell you cast with mana cost {1}{W}{U} will cost {W}{U} to cast.
(wotc • 2006-05-01)
Spells you cast that are both blue and white cost {2} less to cast.
(wotc • 2006-05-01)
Rulings
This reduces only generic mana portion of mana costs. A spell you cast with mana cost {1}{W}{U} will cost {W}{U} to cast.
(wotc • 2006-05-01)
Spells you cast that are both blue and white cost {2} less to cast.
(wotc • 2006-05-01)