Ivan Bazevich is an Acid Generator alpha who escaped from Binghamton during the mass breakout. Sometime later (before his appearance during Alpha Dogs) he began going to alpha-only fights, where he used his alpha ability to blind an opponent. He has not not been seen again and is presumed to be alive. The stench of his attack form was what led Rachel and the team to the location of the fights.
Ivan has the ability to produce an acid-like vomit at will.