Urza's Incubator

Oracle Text

As Urza's Incubator enters the battlefield, choose a creature type.

Creature spells of the chosen type cost 2 less to cast.

Card Rulings

10/4/2004 Multiple Incubators are cumulative.
10/4/2004 You choose a creature type right as it enters the battlefield, before any continuous effects are applied or trigged abilities trigger.