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.
*use fury only when you are sure to create a big difference..like..when using fury can finish the game..and yes..thinking in less than four rounds usually ends the game early in a very unexpected way specially if you use fury..never use it when your opponent still has 12life unless you are sure that he/she can't catch up with your life..and don't use fury when you are not sure of things..remember..it's better to conserve those 3pillz for other cards to use than to waste them..^_^
Dont just randomly use fury. If its first turn, and you go rage, you're screwed unless you've got a badass card to finish up.
Kinjo is a fine Fury Candidate...
but Lost hog is admittedly more Reliable, and Lao Cr more Reliable still.(In ELO)
you always need to access your current situation before making decisions, can't just have a general rule of Always do such and such. some times you don't use Fury with Kinjo... (most of the time actually) it's easier to use the extra 3 pillz later than it is to invest them all on one card.