bloodthirst
 

can someone please explain how does this skill work
will it mean that when I have 0 rage and go into a standard
battle (not hero) I will start with rage ?
thx

Precisely so.

Actually, as soon as the battle ends, the game does a check. If you have more than your guaranteed amount (by bloodthirst) it will gradually go down to that limit, providedyou don't go into another fight. If you have less than your guaranteed amount, it will go up to it.

You can actually have less than your guarenteed amount. This happens if you put on rage gear and then immediately go into combat.

You rage will be set to the minimum every time a mana/rage time interval occurs, or at the end of combat. But if you equip an item, (or finish a set!) that gives rage, then it will only reflect against the minimum once that interval occurs.