Blademaster

Hey guys I just jumped back in to siralim on my vita to help with the hype for siralim2 and i need a little help, im running a chaos bloodlust team and i forgot how to get a blademaster, you know the brownie with the darthmaul swords and the ability that gives it a 40% attack buff and critical after it does 30% or more damage to an enemy, any and all help would be really appreciated.

He is available from the Arena I believe.