The Magnus Lens gives a lowly being the power of a deity. You've acquired it just in time, too, as a horde of enemies is swarming in on your newly-acquired followers.

Look through the Lens, Smite the enemy, and Bless your followers.

Controls are mouse to control the lens, mouse-click to cast your current spell (if you have a charge available). Space bar switches back and forth between Smite and Bless.

Bless heals a random follower unit being looked at through the lens and gives them a temporary boost to their accuracy.

Smite kills a random enemy unit being looked at through the lens.