If the Wizard was able to cast his spell (and it was not cast with irresistible force) the opposing player now has a chance to prevent the spell's effects by attempting to dispel it.
Source: Warhammer Fantasy: 8th Edition
If the Wizard was able to cast his spell (and it was not cast with irresistible force) the opposing player now has a chance to prevent the spell's effects by attempting to dispel it.