Thunderwave

Thunderwave is a spell of low complexity learned by many wizards. An evocation spell, thunderwave creates a blast of sonic energy that can cause bodily harm to any enemies within an area of fifteen feet of the spell, in addition to pushing them backwards, away from the blast zone. The distance a creature caught in the blast is pushed depends upon the caster's degree of self-control and perception. The spell dissipates almost instanteously, but can be recast as many times as the wizard feels fit.