Help with WAR

[Deathgiver]

Isn't fracture total potency 300?

100 initial, 20 potency for 30 seconds = 10 ticks, so 100 + (20x10) = 100 + 200 = 300?

How is that better then a 500 Fell Cleave?

You're comparing it to 1 hit, not to the average gcd. a wars maximum avg gcd pre-buffs at maximum stack usage is (5*248{avg pot of 2 combos} + 500)/6 or 1740/6=290. In reality it's going to be lower than this on anything but dummy fights as you can't just use all your defensive cds for stack whenever they come off cd.