Currently:
Stock -1 for every Leeches in hand.
50% chance one other random card is replaced by Leeches.
Steal 1 Stock from enemy.
If Last card was Leeches, steal 1 more Stock.
I'm not sure this card is very beneficial to the player. If it's the only Leeches in hand, the gain of one leeched stock is canceled out by the effect of the first line. The net effect to stock is that the player loses the one gem and one recruit of its cost and the opponent loses one of all three. If there are two or more Leeches, the player loses more overall stock than the opponent. The best scenario is if two are played in a row with the second drawn as an effect of the first. Then the overall effect is that the player gains (two stock lost + three leeched = ) one stock minus twice the card's cost, and the opponent loses three stock. For two turns and a best-case scenario, I'd want a larger difference than that. Also, being common and with a high chance of replication, taking this into your hand gives you a high likelihood of having three or more.
Perhaps the first line should only take effect if there are two or more? Alternately, is this card not intended to be selected for decks but as an effect of drawing a random Common?