Playing just now I noticed Praxix would use his ability to damage my hero when the card explicitly says the damage should only be dealt to allies:
"4SE: All players discard 3 cards from their decks. Target opposing ally takes X damage, where X was the number of allies discarded, to a maximum of 4."

Playing on PC in browser (firefox latest version) game version 2.850

Should be easy to reproduce, but our game setup was: Praxix vs Aramia. Praxix has Infinity Core and Bazaar in play. Aramia has Aldmor Conduit and Snow Sapphire in play.