Level 1 - Soul Feast
Pick this one up immediately. At Level 7 you'll increase your souls to 150, meaning you can have a ton more health so long as you stay alive in the end game.

Level 4 - Amplified Healing
As Diablo (being a tank) you'll want to be able to soak as much damage as possible without dying. Amplified healing lets you increase this amount by 30%. An easy choice if you ask me, considering again that this Diablo build is all about him being a tank, not a dps machine.

Level 7 - Endless Death
Lets you hold up to 150 souls. Combined with Soul Feast that's an additional 700 health 15 health regen per second. You'll stay alive and make the enemy team wish they were dead.

Level 10 - Lightning Breath
I always choose this over Apocalypse because it's great for protecting your team as well as killing mobs. Nothing is quite as satisfying as hiding around the doubloon trade-in and spewing fire on 5 unsuspecting enemies. Or throwing someone into a corner and lighting them on fire. Lighting Breath is always great when used as an escape or tower defense.

Level 13 - Crippling Shadows
Enemies will try to escape when they see Diablo coming. By slowing them down 25%, they won't be able to. Charge them, grab them, flip the, and kill them. Easy stuff for Mr. Diablo.

Level 16 - Continuous Overpower
Two chances to grab an enemy and BOOM them into submission? Yes please! Rush them, grab them, smash them, grab them, smash them, and then laugh as they rage quit their way into the history books. I love watching Li Li or Illidian try to run away while I grab them endlessly. Silly panda. Crits are for Dibblez.

Level 20 - Hellstorm
The obvious choice if you went with Lightning Breath. However, don't be afraid to choose Storm Shield. That extra shield in late fights is AMAZING. Either choice suits Diablo very well :)

All you need to really know is that 'E' + 'Q' into your forts or your team is god-like. BOOM! HERE COMES THE BOOM!
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