MArcomage

Goblin thief, 3r, Common
Brigand. (Horde.)
Attack: 4
If opponent raised his stock last turn:
enemy stock -3

The stock reduction is too much. As it's written, if your opponent so much as had one resource increase, you would be reducing as many as nine resources in response. Adding this inexpensive Common to a Brigand deck would shut out any deck that is currently able to withstand that keyword. It would also be triggered by some keyword effects.

I would propose instead having it negate the resource gain (max 3). That way, if your opponent increased gems by one, he would instead lose one gem. If he increased recruits by five, he would lose three recruits. If he increased stock by three (or doubled basic production), he would lose three stock.

Regarding your question in the concept notes:

The correct word is "rised" or "rose"? (I have some problems with english tenses)

If used passively, you could say "if your opponent's stock rose" or "if your opponent's stock was raised," but you would never say "rised." The way it's worded now is perfectly clear and correct.

I've modified it to be somehow similar to goblin saboteur.
thanks for the lesson on verbs (anyway "rised" was a typo), I really need to review my english grammar.

This is much more agreeable, I think. I imagine playing it after Prince of Thieves.

Due to fundamental changes to the game since this was first proposed, it would now trigger the effect after standard production occurs. It's needs a revised trigger.