I tried running with Naruto (3 clones), water main, Lee, Tenten. i got around 2k combo and ended up rank 22 by the end (without anbu support), it used exploding hell only about half of the time this time
and since i came prepared with very high focus on def and resist i was able to survive even when he used it (most of the time) with all characters as a level 43.
I still cant say for sure, but the damage done seems to be a factor in terms of how OFTEN he uses it at least, still seems random, but very much less this time.