Darkness Incoming

From BoardGameGeek:

In Darkness Incoming, you play as a wizard's apprentice who stayed behind to try and save the Spire of Aether-your Guild's most ambitious project yet-from a force of unknown creatures bent on destroying it. You play by reinforcing your minions to destroy the enemy forces surrounding the Spire. The enemies surpass you in numbers, but each of your minions possesses specific abilities that make them uniquely capable. Led by the Overseers, the forces of Darkness bring monstrous troops with nightmarish abilities, coming in continuous waves to destroy your minions and the tower where you reside. Make use of powerful spells, minion upgrades, magical scrolls, and a time-bending ritual to defeat the Overseers while fighting their army day and night-before an overwhelming tide engulfs your forces… or die trying. -description from the designer