Omnibian | Magic: The Gathering
Formats Omnibian is Legal in
Official Oracle Text for Omnibian
—Simic research notes
Official Rulings for Omnibian
10/1/2009 : If the target creature is affected by any effects that modify its power or toughness without setting them to specific values (such as from Giant Growth), Omnibian's effect will be applied before those effects. In the example given, the creature will be 6/6.
4/15/2013 : This effect changes only the power, toughness, and creature type of the targeted creature. It does not cause that creature to lose any abilities.