Goblin Mech is the only card which uses 10 mana in the battles. Because it's a 10 mana card his stats are quite satisfying. If you want to have maximum melee attack on the battle then use Daria Dragonscale, Pixie, Pirate Captain and this card will have 9 melee attack + additionally pierce attack where he'll be able to exacute monsters with just one hit. It's not the only card which can have 9 melee attack but it's the uniquest card which have pierce ability. I would say it's the strongest melee monster in the entire game.
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From @smalien