At different intervals, Bloodlust will conjure up your characters' souls in the middle of the screen.
if you click on them, you'll deal some damage to Bloodlust and avoid taking some damage.
If you don't, she'll swallow that character's soul, dealing some damage and healing Bloodlust.
Be careful not to click on spikes as you'll deal damage to your entire party! Spikes will also appear more frequently as you reach later waves.
Now to draw some cute spirits for the entire roster! :D