Playing through Darksiders: Genesis, you will surely see one of those purple spheres fall from your enemies. When you approach them, you receive a prompt to pick them up, and when you do, it tells you that it emits the pulses when you touch it. After that, every time the same enemy drops an orb, officially called a creature core, you have to tap again on the command prompt specifying the number of people you need to complete that particular level.
Creature hearts are beneficial because when you complete a level your characters, War and Conflict, are given new abilities.
For example, if you raise the Phantom Guard creature core to its first level, Strife's shadow clone gains Ricochet Bullets while War Blood Geyser radius increases by 25%. These cores are meant to improve your abilities and each level requires a certain amount of orbs. To get to a higher level, it takes some time.
However, after the first mission you have access to Vulgrim. He is more than happy to provide you with a leveled core for a price. You must give him a set number of Souls and Boatman Parts to unlock them. You can choose to grind the cores or buy them from Vulgrim.
After receiving the hearts, you gain access to the The Creature Hearts tree. You can choose which hearts you want to activate for your riders, increasing their abilities and granting them the improved skills. You receive the best The enemies and The boss elite creature cores.
Creature hearts seem to drop more frequently Enemies you've hit using your Wrath ability or performing a finisher.
