Toughest boosted 4*s?

I can take on most 4* teams in pvp. However I found that Rhulk was particularly challenging when boosted. The 5000 aoe damage for just 9 green was pretty tough. Also boosted iceman is quite challenging as well. Strangely enough, I didn't find boosted jg, hb or cyclops to be that hard, because I could usually down them before they can do too much.
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All of the top 4*s have some of these features, but only two have all 3:
Rulk + iceman. So those are my votes for the hardest to fight both overall and when boosted.
JG is just a tad behind because she is slower (no self acceleration).
Cyclops and imhb are another notch down as they have no ap denial and no aoe, just strong self-acceleration.