With a large set of skills and special abilities at hand it's easy to become overwhelmed. Throw in the fact that Darksiders 2 loves to throw hordes of enemies your direction all this fighting a massive boss, and you may find yourself on the losing end all too often.
The next 5 tips are going to be key to your survival in both Story and Crucible modes.
1: Learn to Dodge - This may seem like an obvious one. And to be honest, it really is. However, I've noticed a lot of players not using dodge correctly. It's not only used to get out of the way. It's also used to give yourself some distance, buying time to unleash devastating specials or heal up. At a certain point you will unlock a dodge ability that unleashes Harvester immediately following a perfect dodge. In other words: learns to dodge already. This isn't God of War.2: Train - At every major city there will be spot for you to train your skills. Also known as spending money to acquire new, more powerful attacks. For the first half of the game or so you won't be needing these, but trust me - you'll die without them. Especially your AoE attacks. These are crucial for those ridiculous mobs that they love to throw your direction.
3: Spend Wisely - Don't go spending your hard earned coin on every new piece of equipment you find. You're going to want to save it for new abilities (read above). Darksiders 2 is a lot like Diablo 3 in that there are a plethora of loot drops for simply slaying your foes. If you aren't able to find equipment strong enough this way then go ahead and spend some cash. I only purchased one piece of equipment through the entire game. So there.
4: Learn to Lock-On - Oh the classic Lock-On button. How you have saved me in so many occasions. In the case of Darksiders 2 however, it's imperative that you learn how to lock and how to not lock. For example, if you are facing a mob of enemies with a single baddie that is spawning them all it's pretty important that you simply lock-on to the captain and take them out.
If you are facing a mob of enemies and notice that your health is low, it's probably smart to not lock-on and simply dodge out of harm's way. Locking on causing the camera to zoom in fairly close and can at times obstruct your view. By unlocking and moving away you can get a better angle of the battlefield. Don't depend on the lock button in every situation.
5: Use Your Crows - This is a special ability I wish I would have discovered earlier in the game. You can unlock the ability to summon a murder of crows to attack your enemy - but that's not all. You can also upgrade them so that they give you health/wrath with every enemy hit. Simply summon the crows when you are low on health, unlock, and dodge away. You'll find yourself full faster than you can imagine.
This is especially important in large boss fights, where health drops are minimal.