Well, most of the time fury seems to be a waste of pillz...
It can be quite useful in many situations:
You have a character with +X life per damage. Using fury means doing at least 4 damages and sometime even more (Kenny with +2 lifes per damage mean you'll get 6 more damages!).
If you apply lesson #2 "thinking in less than 4 rounds", fury is a good and quite unexpected way to reach your KO
Dont use fury at all if you really needs to win most of the forthcoming rounds. You better save thoses 3 pillz to get an attack advantage.
Kinjo and Lost Hog are awful for one hit knockouts. Kinjo especially is dire...can be defeated by almost any deck with few enough pills that it doesn't matter if they're bluffing or not (in ELO, anywho)...
One of the best moves I managed to accomplish with Fury was with Filomena. Her ability was stopped, and without Fury I would have lost by a single point, but the game was won in the third round, because my GHEIST-playing opponent assumed I was trying to get him to waste pills.
Fury is very difficult to use 'correctly', and there is no one way to achieve it...just always remember that it is there as a tool, if you really need it. It's most useful in ELO.
For me, the best way to use fury is, if you calculated that the only way for you to "not lose" the match is, by making it a draw. It also gives you a lot of battle points afterwards. This tactic must only be used when you calculated all of your opponent's options (assumes, bluffs, furies, etc.) and your tactics as well (better think about all of those quick though, because thinking too long might time you out of the game). Assuming that the game is in a "no random" room by the way. It's hard, but you would rather have a draw than to lose a match, right? It kinda frustrates the opponent's confidence and attempt to have that sure win as well. THAT reaction, I would really love to see
Fury is really great for 1 hit KO cards like Kolos or sometimes Hammer
But furry really comes in handy if u use for example Mark or Mojo (cards with lifesteal) cuz then for exampleu hit with Mojo for 3 dmg (u need fury to do that) the oponent loses 3 life (9) and u gain 6 life (1 and if u use Timber thats +1 dmg that is 8:20
so thats when fury becomes really usefull..