Why would anyone want double edged sword mastery?

When you are playing melee champs.

When you get those times where all your enemy does is run and cower under the turret's dick, whats so wrong with wanting to kill them before they reach it?

Its mostly a mastery for glass canons and one shoters. People like akali, who benefit from 1-2-3 you dead, it makes them deal the most damage posible, and since they are squichi, it doesnt matter if they take more damage, they dead anyways

when your positioning as an marksmen is so good that you destroy them before they even get close.

when you're a burst damage dealer and you want to make sure that u can 100-0 them.

i use it when i play zed

Assassins and melee...usually assassins are melee so...

Aatrox has a double edge one that makes him sack hp for more damage

:D ALL these help!

I use it a lot. If i play adc i take it. If the adc has no brain and doesnt position well and thinks hes a melee then yea probably best not to take it. I usually play kha'zix and take it on him. If the guy isnt dead quickly im gonna die regardless so best to take it for most dmg

If you're an assassin or an adc, you might as well take it, you were gonna explode anyway, wether its three seconds or two and a half doesn't make much difference