Mana Clash can be cast on creatures or locations not in line of sight. A mage can cast this spell on creatures in a different room when using the overhead view. This allows the mage to stay out of physical harm by staying out of reach of those creatures.
As a result of the above, Mana Clash is generally strong enough without any sustained abilities or debuffs to kill just about any enemy mage in the game instantly, outside powerful bosses such as Caladrius or Gaxkang
Mana Clash will work on most enemies who have Mana instead of Stamina; it is not limited to mages. These include (but are not limited to) Rage Demons, Desire Demons, Arcane Horrors, Shades, and Abominations. However, some creatures that use magic are invulnerable to this spell (this includes many forms of undead, Revenants, and Pride Demons such as Uldred or The Baroness).