In order to attempt a dispel, the dispelling player first nominates one of his Wizards to make the dispel attempt. Unlike spells, dispels do not have a range and never require the Wizard to see either the target or the caster – you can simply nominate any Wizard on the battlefield.

If the dispelling player does not have an eligible Wizard to attempt a dispel (or simply does not want one of his Wizards to make the attempt) his army can attempt to dispel the spell instead.