I have 25 def atm. Only thing that 20 def has is initiate, and dragon hai robes. 25 i have infinity, frog body, and other small perks. 30 u get turmoil, the upgraded version of initiate, i forget what its called. and i i guess a addy defender.
30 def for turmoil 100% i messed around at 20 def on my now 30 def turmoil pure, don't regret getting turmoil at all. Although its alot of effort its worth it in the end.
Edit : don't you need like 32/33 def for hand cannon? :S