Was playing Arena yesterday and went into a battle.  My combat power should be 40k.  Was looking for an opponent and the moment I went into the screen, my combat power of my team dropped from 40k to 14k.  Went into the game thinking it was a visual bug but none of my set effects worked.  Have lifesteal on one of my characters and it didn't work.  Opponent wasn't using immunity or any block skill stats.