If I have a Master Biomancer out and cast Clever Impersonator without doing his copy effect for the sake of copying him with other clones, will he die as a state-based action or live because he has +1/+1 counters on him? I'm almost completely positive he'd live because of card like Kalonian Hydra or just hydra cards in general. I'm mostly asking to save an argument in the future.
You are correct. Master Biomancer's ability applies a replacement effect to creatures entering the battlefield. This means that the Impersonator is never on the battlefield without the +1/+1 counters granted by Biomancer's ability.
Compare with triggered abilities (e.g. Cathars' Crusade or the Graft ability) which happen after the creature has entered the battlefield; this would be too late for an Impersonator that didn't copy something.
Compare with triggered abilities (e.g. Cathars' Crusade or the Graft ability) which happen after the creature has entered the battlefield; this would be too late for an Impersonator that didn't copy something.